JON O. NEWMAN, Circuit Judge:

This appeal of a judgment dismissing challenges to denials of requests under the Freedom of Information Act ("FOIA") presents important issues arising at the intersection of the public's opportunity to obtain information about their government's activities and the legitimate interests of the Executive Branch in maintaining secrecy about matters of national security. The issues assume added importance because the information sought concerns targeted killings of United States citizens carried out by drone aircraft. Plaintiffs-Appellants The New York Times Company and New York Times reporters Charlie Savage and Scott Shane (sometimes collectively "N.Y. Times"), and the American Civil Liberties Union and the American Civil Liberties Union Foundation (collectively "ACLU") appeal from the January 24, 2013, judgment of the United States District Court for the Southern District of New York (Colleen McMahon, District Judge) dismissing, on motions for summary judgment, their consolidated FOIA suits. See New York Times Co. v. U.S. Dep't of Justice ("Dist. Ct. Op."), 915 F.Supp.2d 508 (S.D.N.Y.2013). The suits were brought against the Defendants-Appellees United States Department of Justice ("DOJ"), the United States Department of Defense ("DOD"), and the Central Intelligence Agency ("CIA") (sometimes collectively the "Government").

We emphasize at the outset that the Plaintiffs' lawsuits do not challenge the lawfulness of drone attacks or targeted killings. Instead, they seek information concerning those attacks, notably, documents prepared by DOJ's Office of Legal Counsel ("OLC") setting forth the Government's reasoning as to the lawfulness of the attacks.

The issues primarily concern the validity of FOIA responses that (a) decline to reveal even the existence of any documents responsive to particular requests (so-called "Glomar responses" (described below)), (b) acknowledge the existence of responsive documents but decline to reveal either the number or description of such documents (so-called "no number, no-list" responses (described below)), (c) assert various FOIA exemptions or privileges claimed to prohibit disclosure of various documents that have been publicly identified, notably the OLC-DOD Memorandum and other OLC legal opinions, and (d) challenge the adequacy of a FOIA search conducted by one office of DOJ.

We conclude that (1) a redacted version of the OLC-DOD Memorandum must be disclosed, (2) a redacted version of the classified Vaughn index (described below) submitted by OLC must be disclosed, (3) other legal opinions prepared by OLC must be submitted to the District Court for in camera inspection and determination of waiver of privileges and appropriate redaction, (4) the Glomar and "no number, no list" responses are insufficiently justified, (5) DOD and CIA must submit Vaughn indices to the District Court for in camera inspection and determination of appropriate disclosure and appropriate redaction, and (6) the Office of Information Policy ("OIP") search was sufficient. We therefore affirm in part, reverse in part, and remand.

Background

The FOIA requests at issue in this case focus primarily on the drone attacks in Yemen that killed Anwar al-Awlaki1 and Samir Khan in September 2011 and al-Awlaki's teenage son, Abdulrahman al-Awlaki, in October 2011. All three victims were United States citizens either by birth or naturalization.

Statutory Framework. FOIA provides, with exceptions not relevant to this case, that an "agency, upon any request for records which (i) reasonably describes such records and (ii) is made in accordance with published rules ..., shall make the records promptly available to any person." 5 U.S.C. § 552(a)(3)(A) (2013). FOIA contains several exemptions, three of which are asserted in this case.

Exemption 1 exempts records that are "(A) specifically authorized under criteria established by an Executive order to be kept secret in the interest of national defense or foreign policy and (B) are in fact properly classified pursuant to such Executive order." 5 U.S.C. § 552(b)(1) (2013). Executive Order 13526 allows an agency to withhold information that (1) "pertains to" one of the categories of information specified in the Executive order, including "intelligence activities (including covert action)," "intelligence sources or methods," or "foreign relations or foreign activities of the United States" and (2) if "unauthorized disclosure of the information could reasonably be expected to cause identifiable and describable damage to the national security." Executive Order No. 13526 § 1.1(a)(3)-(4), 1.4(c)-(d), 75 Fed.Reg. 708, 709 (Dec. 29, 2009).

Exemption 3 exempts records that are "specifically exempted from disclosure by [another] statute" if the relevant statute either "requires that the matters be withheld from the public in such a manner as to leave no discretion on the issue" or "establishes particular criteria for withholding or refers to particular types of matters to be withheld." 5 U.S.C. § 552(b)(3)(A)(i), (ii) (2013). Two such statutes are potentially relevant here. The Central Intelligence Agency Act of 1949, as amended, provides that the Director of National Intelligence "shall be responsible for protecting intelligence sources or methods," and exempts CIA from "any other law which require[s] the publication or disclosure of the organization, functions, names, official titles, salaries, or numbers of personnel employed by the Agency." 50 U.S.C. § 3507 (2013). The National Security Act of 1947, 50 U.S.C. § 3024-1(i)(1) (2013), exempts from disclosure "intelligence sources and methods."

Exemption 5 exempts "inter-agency or intra-agency memorandums or letters which would not be available by law to a party other than an agency in litigation with the agency." 5 U.S.C. § 552(b)(5) (2013). Exemption 5 encompasses traditional common law privileges against disclosure, including the attorney-client and deliberative process privileges. See National Council of La Raza v. Dep't of Justice, 411 F.3d 350, 356 (2d Cir.2005).

The N.Y. Times FOIA requests and Government responses. Shane and Savage, New York Times reporters, submitted separate FOIA requests to OLC. Shane's request, submitted in June 2010, sought:

Joint Appendix ("JA") 296-97.

Savage's request, submitted in October 2010, sought:

JA 300-01.

OLC denied Shane's request, With respect to the portion of his request that pertained to DOD, OLC initially submitted a so-called "no number, no list" response2 instead of submitting the usual Vaughn index,3 numbering and identifying by title and description documents that are being withheld and specifying the FOIA exemptions asserted. A no number, no list response acknowledges the existence of documents responsive to the request, but neither numbers nor identifies them by title or description. OLC said that the requested documents pertaining to DOD were being withheld pursuant to FOIA exemptions 1, 3, and 5.

As to documents pertaining to agencies other than DOD, OLC submitted a so-called "Glomar response."4 This type of response neither confirms nor denies the existence of documents responsive to the request. See Wilner v. National Security Agency, 592 F.3d 60, 68 (2d Cir.2009). OLC stated that the Glomar response was given "because the very fact of the existence or nonexistence of such documents is itself classified, protected from disclosure by statute, and privileged" under 5 U.S.C. § 552(b)(1), (3), (5). CIA confirmed that it requested DOJ to submit a Glomar response on its behalf.5

OLC also denied Savage's request. Declining to submit either a Vaughn index or even a no number, no list response, OLC submitted a Glomar response, stating that, pursuant to Exemptions 1, 3, and 5, it was neither confirming nor denying the existence of documents described in the request. Unlike its letter denying the Shane request, OLC's response to the Savage request did not identify any responsive documents relating to DOD.

During the course of the litigation, OLC modified its responses to the Shane and Savage requests by identifying the existence of one document pertaining to DOD, what the District Court and the parties have referred to as the OLC-DOD Memorandum, but claimed that this document was exempt from disclosure under Exemption 5. Because the OLC-DOD Memorandum was classified, it was presumably also withheld under Exemption 1. As to all other DOD documents, it is not clear whether OLC was continuing to assert a Glomar response, as it had made to Shane, or a no number, no list response, as it had made to Savage.

The ACLU FOIA requests and Government responses. In October 2011, ACLU submitted FOIA requests to three agencies: DOJ (including two of DOJ's component agencies, OIP and OLC), DOD, and CIA. The requests, quoted in the margin,6 sought various documents concerning the targeted killings of United States citizens in general and al-Awlaki, his son, and Khan in particular.

Both OLC and CIA initially submitted Glomar responses, refusing to confirm or deny the existence of responsive documents, pursuant to Exemptions 1, 3, and 5.

DOD initially stated that it could not respond to the request within the statutory time period because of the scope and complexity of the request.

During the course of the litigation, the Government agencies modified their original responses in light of statements by senior Executive Branch officials on the legal and policy issues pertaining to United States counterterrorism operations and the potential use of lethal force by the United States Government against senior operational leaders of al-Qaeda who are United States citizens.

OLC provided ACLU with a Vaughn index of sixty unclassified responsive documents, each described as an e-mail chain reflecting internal deliberations concerning the legal basis for the use of lethal force against United States citizens in a foreign country in certain circumstances. OLC withheld these documents pursuant to Exemption 5.

OLC also submitted a no number, no list response as to classified documents, stating that it could not provide the number or description of these documents because that information was protected from disclosure by Exemptions 1 and 3. OLC did describe one of these documents as an "OLC opinion related to DoD operations," Declaration of John E. Bies, Deputy Assistant Attorney General, OLC ¶ 38 ("Bies Decl."), JA 279, which it withheld in its entirety under Exemptions 1 and 3. This is apparently not the OLC-DOD Memorandum, which OLC said was exempt from disclosure under Exemption 5. That this document is not the OLC-DOD Memorandum is confirmed by OLC's assertion that this document "cannot be further identified or described on the public record." Id. The OLC-DOD Memorandum was withheld under Exemptions 1 and 5.

OIP located one responsive document, a set of talking points prepared for the Attorney General and others related to "hypothetical questions about Anwar al-Aulaqi's death," Declaration of Douglas R. Hibbard, Deputy Chief of the Initial Request Staff, OIP ¶ 8, JA 441, which it released to ACLU. OIP also issued a Vaughn index listing four unclassified records withheld under Exemptions 3, 5, and 6.7 OIP also submitted a no number, no list response to various classified documents withheld under Exemptions 1 and 3.

DOD's revised response disclosed a speech given by Jeh Johnson, then-DOD General Counsel, at Yale Law School on February 22, 2012. DOD also provided ACLU with a Vaughn index listing ten unclassified records, withheld pursuant to Exemption 5. Seven of those documents were e-mail traffic regarding drafts of the speech given by Johnson at Yale Law School and a speech delivered by Attorney General Holder at Northwestern University School of Law. One of the withheld unclassified records was a presentation by Johnson in February 2012, regarding international law principles, to officers who had recently obtained the rank of O7. The remaining two withheld unclassified records were described as "memoranda from the Legal Counsel to the Chairman of the Joint Chiefs of Staff to the White House's National Security Council Legal Advisor addressing the legal basis for conducting military operations against U.S. citizens in general." Declaration of Robert E. Neller, Lt. General, United States Marine Corp, Director of Operations for the Joint Staff at the Pentagon, ¶ 16 ("Neller Decl."). JA 334.

DOD also located responsive classified records. One of these was the previously mentioned OLC-DOD memorandum, which DOD withheld under Exemptions 1 and 5. As to the other classified documents, DOD submitted a no number, no list response.

CIA modified its initial Glomar responses in June 2012 by confirming the existence of "responsive records reflecting a general interest" in two areas described in the ACLU's request: (1) "`the legal basis... upon which U.S. citizens can be subjected to targeted killing'" and (2) "`the process by which U.S. citizens can be subjected to targeted killing.'" Declaration of John Bennett, Director, National Clandestine Service, CIA, ¶ 27 (quoting ACLU request). In these two categories, CIA submitted a no number, no list response, relying on Exemptions 1 and 3, with the exception that CIA acknowledged that it possessed copies of speeches given by the Attorney General at Northwestern University Law School on March 5, 2012, and by the Assistant to the President for Homeland Security and Counterterrorism on April 30, 2012. See id.

The pending lawsuit and District Court opinions. In December 2011, N.Y. Times filed a lawsuit challenging the denials of the Shane and Savage requests. ACLU filed its suit in February 2012. After the suits were consolidated, both Plaintiffs and the Government filed cross-motions for summary judgment. In January 2013, the District Court denied both Plaintiffs' motions for summary judgment and granted the Defendants' motion in both cases, with one exception, which required DOD to submit a more detailed justification as to why the deliberative process exemption (asserted through Exemption 5) applied to two unclassified memos listed in its Vaughn index. See Dist. Ct. Op., 915 F.Supp.2d at 553. Later in January 2013, after receiving a supplemental submission from DOD, the District Court granted the Defendants' motion for summary judgment with respect to the two unclassified DOD memos. See New York Times Co. v. U.S. DOJ ("Dist. Ct. Supp. Op."), Nos. 11 Civ. 9336, 12 Civ. 794, 2013 WL 238928 (S.D.N.Y. Jan.22, 2013).

In its principal opinion, which we discuss in more detail in Parts III and IV, below, the Court first ruled that the Government had conducted an adequate search for responsive documents. See Dist. Ct. Op., 915 F.Supp.2d at 532-33. The Court then considered separately each of the Government's claims to an exemption.

As to Exemption 1, concerning properly classified documents, the Court first ruled that there was no evidence that any of the documents withheld pursuant to Exemption 1 had not been properly classified. See id. at 535. The Court specifically considered the Plaintiffs' claim that legal analysis could not be classified and rejected the claim. See id.

Turning to the Plaintiffs' claim of waiver, the Court, citing Wilson v. CIA, 586 F.3d 171, 186 (2d Cir.2009), first ruled that waiver of Exemption 1 had not occurred with respect to classified documents containing operational details of targeted killing missions. See Dist. Ct. Op., 915 F.Supp.2d at 535-37. The Court then specifically considered whether waiver of Exemption 1 had occurred with respect to the OLC-DOD Memorandum and rejected the claim. See id. at 538.

As to Exemption 3, which protects records exempted from disclosure by statute, the District Court first noted that section 102A(i)(1) of the National Security Act, now codified at 50 U.S.C. § 3024(i)(1) (2013), is an exempting statute within the meaning of Exemption 3, and that this provision protects from disclosure "intelligence sources and methods." Id. at 539. The Court then reckoned with ACLU's contention that placing individuals on kill lists does not fall within the category of intelligence sources and methods. Agreeing with a decision of a district court in the District of Columbia, ACLU v. Dep't of Justice, 808 F.Supp.2d 280, 290-92 (D.D.C.2011) ("Drone Strike Case"), which was later reversed on appeal, see ACLU v. CIA, 710 F.3d 422 (D.C.Cir. 2013), the District Court here rejected ACLU's argument. See Dist. Ct. Op., 915 F.Supp.2d at 540. The District Court then specifically focused on the issue whether legal analysis could fall within the category of intelligence sources and methods. Acknowledging that it is "entirely logical and plausible" that intelligence sources and methods could be redacted from legal analysis upon in camera inspection, the Court declined to make such inspection or resolve the issue because it concluded that Exemption 5 "plainly applies" to the legal analysis that is sought here. See id.

The District Court then determined that section 6 of the CIA Act, 50 U.S.C. § 403g, now codified at 50 U.S.C. § 3507 (2013), is an exempting statute within the meaning of Exemption 3 and that section 6 protects from disclosure information concerning the "functions" of CIA. See id. at 541. Again, following the district court decision in the Drone Strike Case, before it was reversed, the District Court here ruled that Exemption 3 permitted CIA, in response to ACLU's request, to refuse to reveal the existence of records concerning drone strikes. See id.

As to Exemption 5, covering "inter-agency or intra-agency memorandums or letters which would not be available by law to a party other than an agency in litigation with the agency," the District Court noted that this exemption applies to documents withheld "under the deliberative process privilege (a.k.a., the executive privilege) and the attorney-client privilege," citing this Court's decision in Tigue v. U.S. Dep't of Justice, 312 F.3d 70, 76 (2d Cir. 2002). See Dist. Ct. Op., 915 F.Supp.2d at 541-42. OLC relied on the deliberative process privilege to withhold the classified OLC-DOD Memorandum, which both Plaintiffs sought, and DOD relied on this privilege to withhold the two unclassified documents on its Vaughn index that ACLU requested. These two, numbered 9 and 10, were described as "Memorandum from Legal Counsel to Chairman of the Joint Chiefs of Staff to the National Security Legal Advisor with legal analysis regarding the effect of U.S. citizenship on targeting enemy belligerents." JA 409.

With respect to the OLC-DOD Memorandum, the District Court, accepting N.Y. Times's concession that this document at one time might have been properly withheld under the deliberative process and/or attorney-client privileges, see id. at 544, rejected the Plaintiffs' contentions that these privileges had been lost because of one or more of the following principles: waiver, adoption, or working law, see id. at 546-50.

As to documents 9 and 10 on DOD's Vaughn index, the Court initially found DOD's justification for invoking Exemption 5 inadequate, see id. at 545, but ruled that a subsequent submission sufficiently supported the application of the deliberative process privilege and hence Exemption 5 to these documents, see Dist. Ct. Supp. Op., 2013 WL 238928, at *1.

Finally, the District Court considered the Glomar and no number, no list responses that were given by DOJ, DOD, and CIA. Apparently accepting the sufficiency of the affidavits submitted by officials of these agencies to justify the responses under Exemptions 1 and 3, the Court turned its attention to the Plaintiffs' claims that these protections had been waived. Again, following the district court opinion in the Drone Strike Case, before it was reversed, the District Court here concluded that none of the public statements of senior officials waived entitlement to submit Glomar or no number, no list responses because "[i]n none of these statements is there a reference to any particular records pertaining to the [targeted killing] program, let alone the number or nature of those records." Dist. Ct. Op., 915 F.Supp.2d at 553 (emphases in original).

Information made public after the District Court opinions.8 After the District Court entered judgment for the Defendants, one document and several statements of Government officials that the Plaintiffs contend support their claims became publicly available. The document is captioned "DOJ White Paper" and titled "Lawfulness of a Lethal Operation Directed Against a U.S. Citizen Who Is a Senior Operational Leader of Al-Qaida or an Associated Force" ("DOJ White Paper"). As the Government acknowledges, see Br. for Appellees at 25, the 16-page, single-spaced DOJ White Paper was leaked to the press and subsequently officially disclosed by DOJ.9 The leak occurred on February 4, 2013; the official disclosure occurred four days later.

The statements are those of John O. Brennan, Attorney General Eric Holder, and President Obama. Brennan, testifying before the Senate Select Committee on Intelligence on February 7, 2013, on his nomination to be director of CIA, said, among other things, "The Office of Legal Counsel advice establishes the legal boundaries within which we can operate." Open Hearing on the Nomination of John O. Brennan to be Director of the Central Intelligence Agency Before the S. Select Comm. on Intelligence, 113 Cong. 57 (Feb. 7, 2013) ("Brennan Hearing"), available at http://www.intelligence.senate.gov/130207/transcript.pdf. Holder sent a letter to Senator Patrick J. Leahy, Chairman of the Senate Judiciary Committee on May 22, 2013 ("Holder Letter").10 In that letter Holder stated, "The United States ... has specifically targeted and killed one U.S. citizen, Anwar al-Aulaqi," Holder Letter at unnumbered second page, and acknowledged that United States counterterrorism operations had killed Samir Khan and Abdulrahman al-Awlaki, who, he states, were not targeted by the United States, see id. He also stated, "[T]he Administration has demonstrated its commitment to discussing with the Congress and the American people the circumstances in which it could lawfully use lethal force in a foreign country against a U.S. citizen who is a senior operational leader of al-Qaida or its associated forces, and is actively engaged in planning to kill Americans." Id. He also stated, "The decision to target Anwar al-Aulaki was lawful...." Id. at fourth unnumbered page. President Obama delivered an address at the National Defense University on May 23, 2013.11 In that address, the President listed al-Awlaki's terrorist activities and acknowledged that he had "authorized the strike that took him out."

Discussion

I. FOIA Standards.

FOIA calls for "broad disclosure of Government records." CIA v. Sims, 471 U.S. 159, 166, 105 S.Ct. 1881, 85 L.Ed.2d 173 (1985). The disclosure obligation is subject to several exemptions. However, "consistent with the Act's goal of broad disclosure, these exemptions have consistently been given a narrow compass." Dep't of Interior v. Klamath Water Users Protective Ass'n, 532 U.S. 1, 8, 121 S.Ct. 1060, 149 L.Ed.2d 87 (2001) (internal quotation marks omitted). Exemptions 1 (classified documents), 3 (documents protected by statute), and 5 (privileged documents), outlined above, have been invoked in this litigation. "The agency asserting the exemption bears the burden of proof, and all doubts as to the applicability of the exemption must be resolved in favor of disclosure." Wilner, 592 F.3d at 69. To meet its burden of proof, the agency can submit "[a]ffidavits or declarations giving reasonably detailed explanations why any withheld documents fall within an exemption." ACLU v. Dep't of Justice, 681 F.3d 61, 69 (2d Cir.2012) (internal quotation marks omitted).

We review de novo a district court's grant of summary judgment in FOIA litigation. See Wilner, 592 F.3d at 69. When an agency claims that a document is exempt from disclosure, we review that determination and justification de novo. See id. When the claimed exemptions involve classified documents in the national security context, the Court must give "substantial weight to an agency's affidavit concerning the details of the classified status of the disputed record." ACLU, 681 F.3d at 69 (emphasis in original) (internal quotation marks omitted).

II. Appellants' Claims

Narrowing the scope of the Shane request (OLC opinions that address the legal status of targeted killings) and the Savage request (OLC memoranda analyzing the circumstances under which it would be lawful to kill a United States citizen who is deemed to be a terrorist), Appellant N.Y. Times presses on appeal its request to OLC for disclosure of the OLC-DOD memorandum. N.Y. Times also requests a Vaughn index of all withheld documents, instead of the no number, no list and Glomar responses it has received. See Br. for N.Y. Times at 51-52. ACLU seeks disclosure of the OLC-DOD memorandum; what it refers to as "the Unclassified Memos," Br. for ACLU at 50, 61, which are documents nos. 9 and 10 on DOD's Vaughn index, see Dist. Ct. Op., 915 F.Supp.2d at 545; and "certain OLC memoranda that the agencies have not addressed in this litigation but whose existence they have officially acknowledged in public statements," Br. for ACLU at 50. ACLU also requests Vaughn indices and asks that OIP be required "to renew its search for responsive documents." Br. for ACLU at 61.

III. The OLC-DOD Memorandum

The OLC-DOD Memorandum, as described by OLC, is an "OLC opinion pertaining to the Department of Defense marked classified ... [t]hat ... contains confidential legal advice to the Attorney General, for his use in interagency deliberations, regarding a potential military operation in a foreign country." Bies Decl. ¶ 30.

OLC withheld the OLC-DOD Memorandum as protected from disclosure by Exemption 5 "because it is protected by the deliberative process and attorney-client privileges." Id. DOD withheld the document under Exemptions 1 and 5 "because the content of the document contains information about military operations, intelligence sources and methods, foreign government information, foreign relations, and foreign activities." Neller Decl. ¶ 17. General Neller stated that the classified information in the OLC-DOD Memorandum "is not reasonably segregable." Id.

In upholding the application of Exemption 1 to the OLC-DOD Memorandum, the District Court first ruled that the affidavits supplied by senior Government officials demonstrated that classification had been properly made. See Dist. Ct. Op., 915 F.Supp.2d at 535. The Court then ruled that legal analysis may be classified, citing three district court opinions.12 See id. After pointing out that Exemption 1 applies to documents properly classified pursuant to an Executive Order and that Executive Order No. 13526 "applies to any information that `pertains to' military plans or intelligence activities (including covert action), sources or methods," id., the Court stated, "I see no reason why legal analysis cannot be classified pursuant to E.O. 13526 if it pertains to matters that are themselves classified," id.

In considering the application of Exemption 5 to the OLC-DOD Memorandum, the District Court noted the Government's claim that both the deliberative process and attorney-client privileges protected the document, and observed that N.Y. Times did not disagree that the document might at one time have been withheld under both privileges. See id. at 544.

After determining that Exemptions 1 and 5 applied to the OLC-DOD Memorandum, the Court considered and rejected the Plaintiffs' claims that the Government had waived application of these exemptions. With respect to waiver of Exemption 1, the Court stated that waiver occurs only where the government has "officially" disclosed the information sought, Dist. Ct. Op., 915 F.Supp.2d at 536 (citing Halpern v. FBI, 181 F.3d 279, 294 (2d Cir.1999)), and that official disclosure of classified information occurs only if the classified information is "`as specific as the information previously released,'" "`match[es] the information previously disclosed,'" and was "`made public through an official and documented disclosure,'" id. (quoting Wilson, 586 F.3d at 186). The District Court ruled that no official disclosure had been made concerning documents containing operational details of targeted killings, sought by ACLU, see id., and that none of the public pronouncements cited by the Plaintiffs "reveals the necessary detailed legal analysis that supports the Administration's conclusion that targeted killing, whether of citizens or otherwise, is lawful," id. at 538 (footnote omitted).

With respect to waiver of Exemption 5, the District Court ruled that the deliberative process privilege had not been waived because "there is no evidence that the Government continually relied upon and repeated in public the arguments made specifically in the OLC-DOD Memo," id. at 549 (emphasis in original) (internal quotation marks omitted), and that "it is sheer speculation that this particular OLC memorandum... contains the legal analysis that justifies the Executive Branch's conclusion that it is legal in certain circumstances to target suspected terrorists, including United States citizens, for killing away from a `hot' field of battle," id. The Court saw no need to consider the plaintiffs' claim of waiver in the context of the attorney-client privilege because the deliberative process privilege protected the OLC-DOD Memorandum under Exemption 5. See id.

We agree with the District Court's conclusions that the OLC-DOD Memorandum was properly classified and that no waiver of any operational details in that document has occurred. With respect to the document's legal analysis, we conclude that waiver of Exemptions 1 and 5 has occurred.13 "Voluntary disclosures of all or part of a document may waive an otherwise valid FOIA exemption," Dow Jones & Co. v. U.S. Dep't of Justice, 880 F.Supp. 145, 150-51 (S.D.N.Y.1995) (citing Mobil Oil Corp. v. E.P.A., 879 F.2d 698, 700 (9th Cir.1989)), vacated in part on other grounds, 907 F.Supp. 79 (S.D.N.Y.1995), and the attorney-client and deliberative privileges, in the context of Exemption 5, may be lost by disclosure, see Brennan Center for Justice v. U.S. Dep't of Justice, 697 F.3d 184, 208 (2d Cir.2012).

(a) Loss of Exemption 5. Exemption 5 "`properly construed, calls for disclosure of all opinions and interpretations which embody the agency's effective law and policy, and the withholding of all papers which reflect the agency's group thinking in the process of working out its policy and determining what its law shall be.'" Id. at 196 (quoting NLRB v. Sears, Roebuck & Co., 421 U.S. 132, 153, 95 S.Ct. 1504, 44 L.Ed.2d 29 (1975)). At the same time, we recognize that "the law extends the privilege to legal advice given by a lawyer to his client [because] statements by the lawyer often reveal — expressly or by necessary implication — assumptions of fact based on statements by the client," George A. Davidson & William H. Voth, Waiver of the Attorney-Client Privilege, 64 Oregon L.Rev. 637, 650 (1986).

In considering waiver of the legal analysis in the OLC-DOD Memorandum, we note initially the numerous statements of senior Government officials discussing the lawfulness of targeted killing of suspected terrorists, which the District Court characterized as "an extensive public relations campaign to convince the public that [the Administration's] conclusions [about the lawfulness of the killing of al-Awlaki] are correct." Dist. Ct. Op., 915 F.Supp.2d at 524. In a March 25, 2010, speech at the annual meeting of the American Society of International Law in Washington, D.C., then-Legal Adviser of the State Department Harold Hongju Koh said, "U.S. targeting practices, including lethal operations conducted with the use of unmanned aerial vehicles, comply with all applicable law, including the laws of war." JA 113, 124. In a February 22, 2012, speech at the Yale Law School, Jeh Johnson, then-General Counsel of DOD, "summarize[d] ... some of the basic legal principles that form the basis for the U.S. military's counterterrorism efforts against Al Qaeda and its associated forces," JA 399, and referring explicitly to "targeted killing," said, "In an armed conflict, lethal force against known, individual members of the enemy is a long-standing and long-legal practice," JA 402.

In a March 5, 2012, speech at Northwestern University, Attorney General Holder said, "[I]t is entirely lawful — under both United States law and applicable law of war principles — to target specific senior operational leaders of al Qaeda and associated forces." JA 449. He discussed the relevance of the Due Process Clause, id., and maintained that killing a senior al Qaeda leader would be lawful at least in circumstances where

JA 450. Amplifying this last point, he stated that "use of lethal force by the United States will comply with the four fundamental law of war principles governing the use of force: ... necessity[,] ... distinction[,] ... proportionality[,] ... [and] humanity." Id. As the District Court noted, "The Northwestern Speech [by the Attorney General] discussed the legal considerations that the Executive Branch takes into consideration before targeting a suspected terrorist for killing" and "the speech constitutes a sort of road map of the decision-making process that the Government goes through before deciding to `terminate' someone `with extreme prejudice.'" Dist. Ct. Op., 915 F.Supp.2d at 537.

In an April 30, 2012, speech at the Wilson Center in Washington D.C., John O. Brennan, then-Assistant to the President for Homeland Security and Counterterrorism, said, "Yes, in full accordance with the law, and in order to prevent terrorist attacks on the United States and to save American lives, the United States Government conducts drone strikes against specific al-Qaida terrorists, sometimes using remotely piloted aircraft, often referred to publicly as drones." JA 95. On Feb. 7, 2013, Brennan, testifying on his nomination to be director of CIA, said, "The Office of Legal Counsel advice establishes the legal boundaries within which we can operate." Brennan Hearing at 57.

Even if these statements assuring the public of the lawfulness of targeted killings are not themselves sufficiently detailed to establish waiver of the secrecy of the legal analysis in the OLC-DOD Memorandum, they establish the context in which the most revealing document, disclosed after the District Court's decision, should be evaluated. That document is the DOJ White Paper, officially released on Feb. 4, 2013. See note 9, above. Before considering the relevance of the DOJ White Paper to the Government's claim to continued secrecy and privilege of the legal analysis in the OLC-DOD Memorandum, we describe that Memorandum, which we have examined in camera, in some detail.

The OLC-DOD Memorandum is a 41-page classified document, dated July 16, 2010, captioned:

MEMORANDUM FOR THE ATTORNEY GENERAL

Re: Applicability of Federal Criminal Laws and the Constitution to Contemplated Lethal Operations Against Shykh Anwar al-Aulaki14

It was prepared on the letterhead of OLC and signed by David J. Barron, Acting Assistant Attorney General.

The OLC-DOD Memorandum has several parts. After two introductory paragraphs, Part I(A) reports intelligence that OLC has received concerning the relationship between Al-Qaida in the Arabian Peninsula ("AQAP") and al-Qaida, the organization and operation of AQAP, and the role al-Awlaki performs with AQAP. Parts I(B) and I(C) describe the manner in which government agencies would perform the targeted killing of al-Awlaki. Part II(A) considers Title 18 U.S.C. § 1119 (2013), entitled "Foreign murder of United States nationals" and explains why section 1119 does not proscribe killings covered by a traditionally recognized justification. Part II(B) explains why section 1119 incorporates one such justification, the public authority justification. Part III(A) explains why the public authority justification encompasses DOD's role in the contemplated targeted killing, and Part III(B) explains why that justification encompasses another agency's role in the killing. Part IV explains why the contemplated killing would not violate 18 U.S.C. § 956(a) (2013), entitled "Conspiracy to kill, maim, or injure persons or damage property in a foreign country." Part V explains why the contemplated killing would not violate 18 U.S.C. § 2441 (2013), entitled "War crimes." Part VI explains why the contemplated killing would not violate the Fourth or Fifth Amendments of the Constitution.

The 16-page, single-spaced DOJ White Paper virtually parallels the OLC-DOD Memorandum in its analysis of the lawfulness of targeted killings. Like the Memorandum, the DOJ White Paper explains why targeted killings do not violate 18 U.S.C. §§ 1119 or 2441, or the Fourth and Fifth Amendments to the Constitution, and includes an analysis of why section 1119 encompasses the public authority justification. Even though the DOJ White Paper does not discuss 18 U.S.C. § 956(a), which the OLC-DOD Memorandum considers, the substantial overlap in the legal analyses in the two documents fully establishes that the Government may no longer validly claim that the legal analysis in the Memorandum is a secret. After the District Court's decision, Attorney General Holder publicly acknowledged the close relationship between the DOJ White Paper and previous OLC advice on March 6, 2013, when he said at a hearing of the Senate Committee on the Judiciary that the DOJ White Paper's discussion of imminence of threatened action would be "more clear if it is read in conjunction with the underlying OLC advice."15 Oversight of the U.S. Department of Justice Before the Senate Committee on the Judiciary, 113th Cong. (Mar. 6, 2013).

After senior Government officials have assured the public that targeted killings are "lawful" and that OLC advice "establishes the legal boundaries within which we can operate," and the Government makes public a detailed analysis of nearly all the legal reasoning contained in the OLC-DOD Memorandum, waiver of secrecy and privilege as to the legal analysis in the Memorandum has occurred.

The recent opinion of the District Court for the Northern District of California, First Amendment Coalition v. U.S. Dep't of Justice, No. 4:12-cv-01013-CW, 2014 WL 1411333 (N.D.Cal. April 11, 2014), denying an FOIA request for the OLC-DOD Memorandum, is readily distinguishable because the Court, being under the impression that "there has been no `official disclosure' of the White Paper," id., 2014 WL 1411333 at 12, did not assess its significance, whereas in our case, the Government has conceded that the White Paper, with its detailed analysis of legal reasoning, has in fact been officially disclosed, see footnote 10, supra.

In resisting disclosure of the OLC-DOD Memorandum, the Government contends that making public the legal reasoning in the document will inhibit agencies throughout the Government from seeking OLC's legal advice. The argument proves too much. If this contention were upheld, waiver of privileges protecting legal advice could never occur. In La Raza, we explained that "[l]ike the deliberative process privilege, the attorney-client privilege may not be invoked to protect a document adopted as, or incorporated by reference into, an agency's policy." 411 F.3d at 360. Here, the Government has done so by publicly asserting that OLC advice "establishes the legal boundaries within which we can operate"; it "cannot invoke that relied-upon authority and then shield it from public view." Brennan Center, 697 F.3d at 207-08. Agencies seeking OLC legal advice are surely sophisticated enough to know that in these circumstances attorney/client and deliberative process privileges can be waived and the advice publicly disclosed. We need not fear that OLC will lack for clients.

The Government also argues that because the OLC-DOD Memorandum refers to earlier OLC documents that remain classified, those assessing the legal reasoning in the OLC-DOD Memorandum might find the reasoning deficient without an opportunity to see the previous documents. However, the reasoning in the OLC-DOD Memorandum is rather elaborate, and readers should have no difficulty assessing the reasoning on its own terms. Moreover, the Government had no similar concern when it released the DOJ White Paper, the reasoning of which cannot be properly assessed, on the Government's argument, without seeing the OLC-DOD Memorandum. Finally, the Government always has the option of disclosing redacted versions of previous OLC advice.

The loss of protection for the legal analysis in the OLC-DOD Memorandum does not mean, however, that the entire document must be disclosed. FOIA provides that "[a]ny reasonably segregable portion of a record shall be provided to any person requesting such record after deletion of the portions which are exempt under this subsection." 5 U.S.C. § 552b. The Government's waiver applies only to the portions of the OLC-DOD Memorandum that explain legal reasoning. These are Parts II, III, IV, V, and VI of the document, and only these portions will be disclosed. Even within those portions of the document, there are matters that the Government contends should remain secret for reasons set forth in the Government's classified ex parte submission, which we have reviewed in camera.

One of those reasons concerns [redacted] the Government persuasively argues warrants continued secrecy. [redacted] We will redact all references to that [redacted].16

Two arguments concern facts mentioned within the legal reasoning portions of the OLC-DOD Memorandum that no longer merit secrecy. One is the identity of the country in which al-Awlaki was killed. However, numerous statements by senior Government officials identify that country as Yemen. On September 30, 2011, DOD released a transcript reporting then-Secretary of Defense Panetta stating, "[W]e've been working with the Yemenis over a long period of time to be able to target Awlaki, and I want to congratulate them on their efforts, their intelligence assistance, their operational assistance to get the job done." JA 799. On October 25, 2011, President Obama, appearing on a network television program, said, referring to al-Awlaki, "[I]t was important that, working with the [Yemenis,]17 we were able to remove him from the field." Transcript of The Tonight Show with Jay Leno (Oct. 25, 2011). JA 556. On the day al-Awlaki was killed, September 3, 2011, DOD's Armed Forces Press Service reported, "A U.S. airstrike that killed Yemeni-based terrorist Anwar al-Awlaki early this morning is a testament to the close cooperation between the United States and Yemen, Defense Secretary Leon E. Panetta said today." JA 651. The report continued, "Obama and Panetta congratulated the Yemenis on their intelligence and operational assistance in targeting [al-] Awlaki." Id. It is no secret that al-Awlaki was killed in Yemen. However, the OLC-DOD Memorandum contains some references to the Yemeni government that are entitled to secrecy and will be redacted.

The other fact within the legal reasoning portion of the OLC-DOD Memorandum that the Government contends merits secrecy is the identity of the agency, in addition to DOD, that had an operational role in the drone strike that killed al-Awlaki. Both facts were deleted from the April 21 public opinion, but have been restored in this opinion. Apparently not disputing that this fact has been common knowledge for some time, the Government asserts the importance of concealing any official recognition of the agency's identity. The argument comes too late.

A March 18, 2010, Wall Street Journal article quotes Panetta, then CIA Director:

"Drone Kills Suspect in CIA Suicide Bombing," The Wall Street Journal (Mar. 18, 2010). Although the reference to "we" is not unequivocally to CIA and might arguably be taken as a reference to the Government generally, any doubt on this score was eliminated three months later.

In a June 27, 2010, interview with Jake Tapper of ABC News, Panetta said:

Tr. of This Week telecast, available at http://abcnews.go.com/ThisWeek/weektranscriptpanetta/story?id=11025299&singlePage=true.

On October 7, 2011, Panetta, then Secretary of Defense, was quoted as saying in a speech to sailors and Marines at the United States Navy's 6th Fleet headquarters in Naples, "Having moved from the CIA to the Pentagon, obviously I have a hell of a lot more weapons available to me in this job than I had at the CIA, although the Predators aren't bad." "U.S.: Defense secretary refers to CIA drone use," Los Angeles Times (Oct. 7, 2011).

On January 29, 2012, the following occurred when Secretary of Defense Panetta was interviewed by Scott Pelley on the CBS television program "60 Minutes":

Asked, "You killed al-Awlaki?" Panetta "nodded affirmatively," as described by the District Court, see Dist. Ct. Op., 915 F.Supp.2d at 530. Then, when asked about identifying for killing a person who has been identified as an enemy combatant, Panetta says, "It's a recommendation we make, it's a recommendation the CIA director makes in my prior role ... the President of the United States has to sign off." Web Extra presentation, available at http://www.cbsnews.com/video/watch/?id=7396830n, at 0:01, 2:30. CIA's former director has publicly acknowledged CIA's role in the killing of al-Awlaki.

On February 7, 2014, Rep. Mike Rogers, chairman of the House Select Committee on Intelligence, disclosed that his committee has overseen the CIA's targeted-killing strikes since "even before they conducted that first air strike that took Awlaki." Transcript, Face the Nation, CBS News (Feb. 10, 2013), http://cbsn.ws/ZgB9R.

On February 11, 2014, the following exchange occurred between Senator Bill Nelson and James R. Clapper, Director of National Intelligence, at a hearing of the Senate Armed Services Committee:

Testimony on Current and Future Worldwide Threats to the National Security of the United States, Hearing Before the Senate Armed Services Comm., 113th Cong. 37 (2014), available at http://www.armedservices.senate.gov/imo/media/doc.14-07-2-11-14.pdf. It is no secret that CIA has a role in the use of drones.

(b) Loss of Exemption 1. Much of the above discussion concerning loss of Exemption 5 is applicable to loss of Exemption 1. As the District of Columbia Circuit has noted, "Ultimately, an agency's justification for invoking a FOIA exemption is sufficient if it appears `logical' or `plausible.'" Wolf v. CIA, 473 F.3d 370, 374-75 (D.C.Cir.2007) (quoting Gardels v. CIA, 689 F.2d 1100, 1105 (D.C.Cir.1982)). But Gardels made it clear that the justification must be "logical" and "plausible" "in protecting our intelligence sources and methods from foreign discovery." 689 F.2d at 1105.

The District Court noted the Government's contention that "`[i]t is entirely logical and plausible that the legal opinion contains information pertaining to military plans, intelligence activities, sources and methods, and foreign relations.' (Gov't Memo. in Opp'n/Reply 6)." Dist. Ct. Op., 915 F.Supp.2d at 540. But the Court then astutely observed, "[T]hat begs the question. In fact, legal analysis is not an `intelligence source or method.'" Id.

We recognize that in some circumstances the very fact that legal analysis was given concerning a planned operation would risk disclosure of the likelihood of that operation, but that is not the situation here where drone strikes and targeted killings have been publicly acknowledged at the highest levels of the Government. We also recognize that in some circumstances legal analysis could be so intertwined with facts entitled to protection that disclosure of the analysis would disclose such facts. Aware of that possibility, we have redacted, as explained above, the entire section of the OLC-DOD Memorandum that includes any mention of intelligence gathering activities. The only other facts mentioned in the pure legal analysis portions of the OLC-DOD Memorandum — the identification of the country where the drone strike occurred and CIA's role — have both already been disclosed, also as explained above. With respect to disclosure of CIA's role, we can be confident that neither Senator Dianne Feinstein, Chairman of the Senate Select Committee on Intelligence, nor Representative Mike Rogers, Chairman of the House Select Committee on Intelligence, thought they were revealing a secret when they publicly discussed CIA's role in targeted killings by drone strikes.18

The three-part test for "official" disclosure, relevant to Exemption 1, which the District Court took from Wilson, 586 F.3d at 186, has been sufficiently satisfied. The legal analysis in the OLC-DOD Memorandum is "`as specific as the information previously released'" in the DOJ White Paper, it "`match[es] the information previously disclosed,'" and was "`made public through an official and documented disclosure.'" Dist. Ct. Op., 915 F.3d at 536 (quoting Wilson, 586 F.3d at 186). In reaching this conclusion, we do not understand the "matching" aspect of the Wilson test to require absolute identity. Indeed, such a requirement would make little sense. A FOIA requester would have little need for undisclosed information if it had to match precisely information previously disclosed.19

With the redactions and public disclosures discussed above, it is no longer either "logical" or "plausible" to maintain that disclosure of the legal analysis in the OLC-DOD Memorandum risks disclosing any aspect of "military plans, intelligence activities, sources and methods, and foreign relations." The release of the DOJ White Paper, discussing why the targeted killing of al-Awlaki would not violate several statutes, makes this clear. The additional discussion of 18 U.S.C. § 956(a) in the OLC-DOD Memorandum adds nothing to the risk. Whatever protection the legal analysis might once have had has been lost by virtue of public statements of public officials at the highest levels and official disclosure of the DOJ White Paper.

IV. Legal Analysis in Other Withheld Documents20

In addition to seeking at least the legal analysis in the OLC-DOD Memorandum, ACLU also seeks disclosure of the legal analysis in documents numbered 9 and 10 on DOD's unclassified Vaughn index and in other OLC legal memoranda the existence of which ACLU contends have been officially acknowledged in public statements. See Br. for ACLU at 50. ACLU contends that Senator Feinstein said at the confirmation hearing of Brennan to be CIA director that there are eleven such memoranda, see id. at 50 n. 25, of which four were provided to the Senate Select Committee on Intelligence, see id. at 24 & n. 9.

Documents numbered 9 and 10 are DOD legal memoranda, which were made available to this Court ex parte for in camera inspection. As to these documents, we agree with the District Court that the declaration of Richard C. Gross, Brigadier General, United States Army, JA 863, adequately supports the application of Exemption 5. See Dist. Ct. Supp. Op., 2013 WL 238928, at *1. As General Gross pointed out, these brief documents (two and four pages respectively) are informal and predecisional. One does not even identify the sender or the receiver. They mention legal authorities, but in no way resemble the detailed, polished legal analysis in the disclosed DOJ White Paper. At most, they are "part of a process by which governmental decisions and policies are formulated, [or] the personal opinions of the writer prior to the agency's adoption of a policy." Public Citizen, Inc. v. Office of Management and Budget, 598 F.3d 865, 875 (D.C.Cir.2010) (alteration in original) (internal quotation marks omitted). See also Judicial Watch, Inc. v. FDA, 449 F.3d 141, 151 (D.C.Cir.2006) (protecting as deliberative "the give-and-take of the consultative process") (internal quotation marks omitted). No waiver of Exemption 5 has occurred with respect to these two documents.

The other OLC legal memoranda have not been submitted to this Court for in camera inspection, and we are therefore unable to adjudicate the waiver issue as to these memoranda, nor determine, if waiver has occurred, what portions of these documents must be redacted. It is possible that waiver of any claimed privileges applies to the legal reasoning in these documents for the same reasons applicable to the OLC-DOD Memorandum. On remand, these memoranda must be produced to the District Court for in camera examination and determination of waiver and appropriate redaction, in light of our rulings with respect to disclosure and redaction of the legal reasoning in the OLC-DOD Memorandum.

V. Glomar and No Number, No List Responses

As set forth above, OLC, DOD, and CIA submitted either Glomar or no number, no list responses to the N.Y. Times and ACLU requests, in addition to Vaughn indices. For clarification, we set forth in the margin a chart showing the revised responses of the three agencies.21 An agency may withhold information on the number of responsive documents and a description of their contents if those facts are protected from disclosure by a FOIA exemption. See Wilner, 592 F.3d at 67-69; Hayden v. National Security Agency, 608 F.2d 1381, 1384 (D.C.Cir.1979). However, we agree with the D.C. Circuit that "[s]uch a response would only be justified in unusual circumstances, and only by a particularly persuasive affidavit." ACLU, 710 F.3d at 433.

The Government's core argument to justify the Glomar and no number, no list responses, as it was with the effort to withhold the OLC-DOD Memorandum, is that identification of any document that provides legal advice to one or more agencies on the legality of targeted killings "would tend to disclose the identity of the agency or agencies that use targeted lethal force against certain terrorists who are U.S. citizens...." Br. for Appellees at 37. If one of those agencies is CIA, the Government's argument continues, disclosure of any information in a Vaughn index that "would tend to disclose the identity" of that agency must be protected because, the Government claims, "[T]he government has never disclosed (with the exception of the Bin Laden operation) whether the CIA has an operational role in the use of targeted lethal force or is authorized to use such force." Id. at 38.

As was true of waiver of privileges that might originally have protected the legal reasoning in the OLC-DOD Memorandum, the statements of Panetta when he was Director of CIA and later Secretary of Defense, set forth above, have already publicly identified CIA as an agency that had an operational role in targeted drone killings.22 With CIA identified, the Appellees' main argument for the use of Glomar and no number, no list responses evaporates. The Vaughn index submitted by OLC in camera must be disclosed, and DOD and CIA must submit classified Vaughn indices to the District Court on remand for in camera inspection and determination of appropriate disclosure and appropriate redaction.

As was also true of the OLC-DOD Memorandum, however, the requirement of disclosing the agencies' Vaughn indices does not necessarily mean that either the number or the listing of all documents on those indices must be disclosed. The Appellees argue persuasively that with respect to documents concerning a contemplated military operation, disclosure of the number of such documents must remain secret because a large number might alert the enemy to the need to increase efforts to defend against attacks or to avoid detection and a small number might encourage a lessening of such efforts. Accordingly, all listings after number 271 on OLC's Vaughn index will remain secret. See Wilner, 592 F.3d at 70 (upholding Glomar response as to identification of documents that would reveal "details of [a] program's operations and scope"). The descriptions of listing numbers 1-4, 6, 69, 72, 80-82, 87, 92, 103-04, 244-49, and 256 reveal information entitled to be protected. Listing numbers 10-49, 51-56, 84-86, 94, 101, 106-09, 111-12, 114-15, 251, 255, 257-61, and 266-67 describe email chains (or copies of chains). Because the Plaintiffs informed the District Court that they were not seeking these items, see Dist. Ct. Op., 915 F.Supp.2d at 545, these listings need not be disclosed.

No reason appears why the number, title, or description of the remaining listed documents needs to be kept secret. Listing number 5 is the OLC-DOD Memorandum; listing numbers 7-9, 50, 250, 262-65, and 269-71 describe documents and attorney notes concerning legal advice; listing numbers 57-68, 70-71, 73-79, 83, 88-91, 93, 95-100, 102, 105, 110, 113, 116-22, and 144-45 are described as including factual information concerning al-Awlaki; listing numbers 123-30 are described as unclassified open source materials; listing numbers 131-43 and 148-237 are described as drafts of the OLC-DOD Memorandum; listing numbers 238-43 are described as drafts of other documents; listing numbers 146-47 are described as drafts of Document 86A, a listing that does not appear on the OLC's Vaughn index; and listing numbers 252-54 and 268 are described as including [redacted]23.

Some, perhaps all, of the information in many of these documents might be protected as classified intelligence information or predecisional. If the Plaintiffs challenge the applicability of a cited exemption, the District Court, after in camera inspection, will be able to determine which of these documents need to be withheld and which portions of these documents need to be redacted as subject to one or more exemptions that have not been waived. At this stage, we decide only that the number, title, and description of all documents listed on OLC's classified Vaughn index must be disclosed, with the exception of listing numbers 1-4, 6, 69, 72, 80-82, 87, 92, 103-04, 244-49; 10-49, 51-56, 84-86, 94, 101, 106-09, 111-12, 114-15, 251, 252-54, 255-61, 266-67, 268; and all listings after listing number 271.

Unlike OLC, DOD and CIA did not provide this Court with classified Vaughn indices, and we are unable to distinguish among listed document numbers, which titles or descriptions merit secrecy. We will therefore direct that, upon remand, DOD and CIA will provide the District Court with classified Vaughn indices listing documents responsive to the Plaintiffs' requests. From these indices, the District Court, with the guidance provided by this opinion, should have little difficulty, after examining whatever further affidavits DOD and CIA care to submit to claim protection of specific listings, to determine which listings on these indices may be disclosed. See ACLU, 710 F.3d at 432 (prescribing a similar procedure after rejecting a Glomar response).

VI. Adequacy of OIP's Search

Finally, ACLU argues that OIP did not make an adequate search because it did not disclose thirty e-mail chains with other DOJ offices that were found during OLC's search for responsive records. See Br. for ACLU at 60. However, as this Court has recognized, a search is not inadequate merely because it does not identify all responsive records. See Grand Central Partnership, Inc. v. Cuomo, 166 F.3d 473, 489 (2d Cir.1999). The adequacy of a search is not measured by its results, but rather by its method. See Weisberg v. U.S. Dep't of Justice, 745 F.2d 1476, 1485 (D.C.Cir.1984). To show that a search is adequate, the agency affidavit "must be relatively detailed and nonconclusory, and submitted in good faith." Grand Central Partnership, 166 F.3d at 489 (internal quotation marks omitted). The affidavit submitted by an OIP official, JA 412-419 ¶¶ 7-34, easily meets these requirements, and the November 3, 2011, cutoff date was reasonable as the date on which the search was commenced. See Edmonds Institute v. U.S. Dep't of Interior, 383 F.Supp.2d 105, 110-11 (D.D.C. 2005).

Conclusion

For the reasons stated above, we conclude that:

We therefore affirm in part, reverse in part, and remand.24

Appendix A

OLC-DOD Memorandum after appropriate redactions and deletion of classification codes (redactions in the OLC-DOD Memorandum are indicated by white spaces)

Office of the Assistant Attorney General

Washington, D.C. 20530

July 16, 2010

MEMORANDUM FOR THE ATTORNEY GENERAL

Re: Applicability of Federal Criminal Laws and the Constitution to Contemplated Lethal Operations Against Shaykh Anwar al-Aulaqi

II.

We begin our legal analysis with a consideration of section 1119 of title 18, entitled "Foreign murder of United States nationals." Subsection 1119(b) provides that "[a] person who, being a national of the United States, kills or attempts to kill a national of the United States while such national is outside the United States but within the jurisdiction of another country shall be punished as provided under sections 1111, 1112, and 1113." 18 U.S.C. § 1119(b).6 In light of the nature of the contemplated operations described above, and the fact that their target would be a "national of the United States" who is outside the United States, we must examine whether section 1119(b) would prohibit those operations. We first explain, in this part, the scope of section 1119 and why it must be construed to incorporate the public authority justification, which can render lethal action carried out by a governmental official lawful in some circumstances. We next explain in part III-A why that public authority justification would apply to the contemplated DoD operation. Finally, we explain in part III-13 why that justification would apply to the contemplated CIA operation. As to each agency, we focus on the particular circumstances in which it would carry out the operation.

A.

Although section 1119(b) refers only to the "punish[ments]" provided under sections 1111, 1112, and 1113, courts have construed section 1119(b) to incorporate the substantive elements of those cross-referenced provisions of title 18. See, e.g., United States v. Wharton, 320 F.3d 526, 533 (5th Cir.2003); United States v. White, 51 F.Supp.2d 1008, 1013-14 (E.D.Ca.1997). Section 1111 of title 18 sets forth criminal penalties for "murder," and provides that linjurder is the unlawful killing of a human being with malice aforethought. Id. § 1111(a). Section 1112 similarly provides criminal sanctions for "manslaughter," and states that "[m]anslaughter is the unlawful killing of a human being without malice." Id. § 1112. Section 1113 provides criminal penalties for "attempts to commit murder or manslaughter." Id. § 1113. It is therefore clear that section 1119(b) bars only "unlawful killings."7

This limitation on section 1119(b)'s scope is significant, as the legislative history to the underlying offenses that the section incorporates makes clear. The provisions section 1119(b) incorporates derive from sections 273 and 274 of the Act of March 4, 1909, ch. 321, 35 Stat. 1088, 1143. The 1909 Act codified and amended the penal laws of the United States. Section 273 of the enactment defined murder as "the unlawful killing of a human being with malice aforethought," and section 274 defined manslaughter as "the unlawful killing of a human being without malice." 35 Stat. 1143.8 In 1948, Congress codified the federal murder and manslaughter provisions at sections 1111 and 1112 of title 18 and retained the definitions of murder and manslaughter in nearly identical form, see Act of June 25, 1948, ch. 645, 62 Stat. 683, 756, including the references to "unlawful killing" that remain in the statutes today — references that track similar formulations in some state murder statutes.9

As this legislative history indicates, guidance as to the meaning of what constitutes an "unlawful killing"-in sections 1111 and 1112 — and thus for purposes of section 1119(b) — can be found in the historical understandings of murder and manslaughter. That history shows that states have long recognized justifications and excuses to statutes criminalizing "unlawful" killings.10 One state court, for example, in construing that state's murder statute explained that "the word `unlawful' is a term of art" that "connotes a homicide with the absence of factors of excuse or justification," People v. Frye, 7 Cal.App.4th 1148, 10 Cal.Rptr.2d 217, 221 (1992). That court further explained that the factors of excuse or justification in question include those that have traditionally been recognized, id. at 221 n. 2. Other authorities support the same conclusion. See, e.g., Mullaney v. Wilbur, 421 U.S. 684, 685, 95 S.Ct. 1881, 44 L.Ed.2d 508 (1975) (requirement of "unlawful" killing in Maine murder statute meant that killing was "neither justifiable nor excusable"); cf. also Rollin M. Perkins & Ronald N. Boyce, Criminal Law 56 (3d ed. 1982) ("Innocent homicide is of two kinds, (1) justifiable and (2) excusable.").11 Accordingly, section 1119 does not proscribe killings covered by a justification traditionally recognized, such as under the common law or state and federal murder statutes. See White, 51 F.Supp.2d at 1013 ("Congress did not intend [section 1119] to criminalize justifiable or excusable killings.").

B.

Here, we focus on the potential application of one such recognized justification — the justification of "public authority" — to the contemplated DoD and CIA operations. Before examining whether, on these facts, the public authority justification would apply to those operations, we first explain why section 1119(b) incorporates that particular justification.

The public authority justification, generally understood, is well-accepted, and it is clear it may be available even in cases where the particular criminal statute at issue does not expressly refer to a public authority justification.12 Prosecutions where such a "public authority" justification is invoked are understandably rare, see American Law Institute, Model Penal Code and Commentaries § 3.03 Comment 1, at 24 (1985); cf. VISA Fraud Investigation, 8 Op. O.L.C. 284, 285 n. 2, 286 (1984), and thus there is little case law in which courts have analyzed the scope of the justification with respect to the conduct of government officials.13 Nonetheless, discussions in the leading treatises and in the Model Penal Code demonstrate its legitimacy. See 2 Wayne R. LaFave, Substantive Criminal Law § 10.2(b), at 135 (2d ed.2003); Perkins & Boyce, Criminal Law at 1093 ("Deeds which otherwise would be criminal, such as taking or destroying property, taking hold of a person by force and against his will, placing him in confinement, or even taking his life, are not crimes if done with proper public authority."); see also Model Penal Code § 3.03(I)(a), (d), (e), at 22-23 (proposing codification of justification where conduct is "required or authorized by," inter alia, "the law defining the duties or functions of a public officer ..."; "the law governing the armed services or the lawful conduct of war"; or "any other provision of law imposing a public duty"); National Comm'n on Reform of Federal Criminal Laws, A Proposed New Federal Criminal Code § 602(1) ("Conduct engaged in by a public servant in the course of his official duties is justified when it is required or authorized by law."). And this Office has invoked analogous rationales in several instances in which it has analyzed whether Congress intended a particular criminal statute to prohibit specific conduct that otherwise falls within a government agency's authorities.14

The public authority justification does not excuse all conduct of public officials from all criminal prohibitions. The legislature may design some criminal prohibitions to place bounds on the kinds of governmental conduct that can be authorized by the Executive. Or, the legislature may enact a criminal prohibition in order to delimit the scope of the conduct that the legislature has otherwise authorized the Executive to undertake pursuant to another statute.15 But the recognition that a federal criminal statute may incorporate the public authority justification reflects the fact that it would not make sense to attribute to Congress the intent with respect to each of its criminal statutes to prohibit all covered activities undertaken by public officials in the legitimate exercise of their otherwise lawful authorities, even if Congress has clearly intended to make those same actions a crime when committed by persons who are not acting pursuant to such public authority. In some instances, therefore, the better view of a criminal prohibition may well be that Congress meant to distinguish those persons who are acting pursuant to public authority, at least in some circumstances, from those who are not, even if the statute by terms does not make that distinction express. Cf. Nardone v. United States, 302 U.S. 379, 384, 58 S.Ct. 275, 82 L.Ed. 314 (1937) (federal criminal statutes should be construed to exclude authorized conduct of public officers where such a reading "would work obvious absurdity as, for example, the application of a speed law to a policeman pursuing a criminal or the driver of a fire engine responding to an alarm").16

Here, we consider a federal murder statute, but there is no general bar to applying the public authority justification to such a criminal prohibition. For example, with respect to prohibitions on the unlawful use of deadly force, the Model Penal Code recommended that legislatures should make the public authority (or "public duty") justification available, though only where the use of such force is covered by a more particular justification (such as defense of others or the use of deadly force by law enforcement), where the use of such force "is otherwise expressly authorized by law," or where such force "occurs in the lawful conduct of war." Model Penal Code § 3.03(2)(b), at 22; see also id. Comment 3, at 26. Some states proceeded to adopt the Model Penal Code recommendation.17 Other states, although not adopting that precise formulation, have enacted specific statutes dealing with the question of when public officials are justified in using-deadly force, which often prescribe that an officer acting in the performance of his official duties must reasonably have believed that such force was "necessary."18 Other states have more broadly provided that the public authority defense is available where the government officer engages in a "reasonable exercise" of his official functions.19 There is, however, no federal statute that is analogous, and neither section 1119 nor any of the incorporated title 18 provisions setting forth the substantive elements of the section 1119(b) offense, provide any express guidance as to the existence or scope of this justification.

Against this background, we believe the touchstone for the analysis of whether section 1119 incorporates not only justifications generally, but also the public authority justification in particular, is the legislative intent underlying this criminal statute. We conclude that the statute should be read to exclude from its prohibitory scope killings that are encompassed by traditional justifications, which include the public authority justification. There are no indications that Congress had a contrary intention. Nothing in the text or legislative history of sections 1111-1113 of title 18 suggests that Congress intended to exclude the established public authority justification from those that Congress otherwise must be understood to have imported through the use of the modifier "unlawful" in those statutes (which, as we explain above, establish the substantive scope of section 1119(b)).20 Nor is there anything in the text or legislative history of section 1119 itself to suggest that Congress intended to abrogate or otherwise affect the availability under that statute of this traditional justification for killings. On the contrary, the relevant legislative materials indicate that in enacting section 1119 Congress was merely closing a gap in a field dealing with entirely different kinds of conduct than that at issue here.

The origin of section 1119 was a bill entitled the "Murder of United States Nationals Act of 1991," which Senator Thurmond introduced during the 102d Congress in response to the murder of an American in South Korea who had been teaching at a private school there. See 137 Cong. Rec. 8675-77 (1991) (statement of Sen, Thurmond), Shortly after the murder, another American teacher at the school accused a former colleague (who was also a U.S. citizen) of having committed the murder, and also confessed to helping the former colleague cover up the crime. The teacher who confessed was convicted in a South Korean court of destroying evidence and aiding the escape of a criminal suspect, but the individual she accused of murder had returned to the United States before the confession. Id. at 8675 The United States did not have an extradition treaty with South Korea that would have facilitated prosecution of the alleged murderer and therefore, under then-existing law, "the Federal Government ha[d] no jurisdiction to prosecute a person residing in the United States who ha[d] murdered an American abroad except in limited circumstances, such as a terrorist murder or the murder of a Federal official." Id.

To close the "loophole under Federal law which permits persons who murder Americans in certain foreign countries to go punished," id, the Thurmond bill would have added a new section to title 18 providing that "[w]hoever kills or attempts to kill a national of the United States while such national is outside the United States but within the jurisdiction of another country shall be punished as provided under sections 1111, 1112, and 1113 of this title." S. 861, 102d Cong. (1991) (incorporated in S. 1241, 102d Cong. §§ 3201-03 (1991)). The proposal also contained a separate provision amending the procedures for extradition "to provide the executive branch with the necessary authority, in the absence of an extradition treaty, to surrender to foreign governments those who commit violent crimes against U.S. nationals." 137 Cong. Rec. 8676 (1991) (statement of Sen. Thurmond) (discussing S. 861, 102d Cong., § 3).21 The Thurmond proposal was incorporated into an omnibus crime bill that both the House and Senate passed, but that bill did not become law.

In the 103d Congress, a revised version of the Thurmond bill was included as part of the Violent Crime Control and Law Enforcement Act of 1994. H.R. 3355 § 60009, 103d Cong. (1994). The new legislation differed from the previous bill in two key respects. First, it prescribed criminal jurisdiction only where both the perpetrator and the victim were U.S. nationals, whereas the original Thurmond bill would have extended jurisdiction to all instances in which the victim was a U.S. national (based on so-called "passive personality" jurisdiction22). Second, the revised legislation did not include the separate provision from the earlier Thurmond legislation that would have amended the procedures for extradition. Congress enacted the revised legislation in 1994 as part of Public Law No. 103-322, and it was codified as section 1119 of title 18. See Pub.L. No. 103-322, § 60009, 108 Stat. 1796, 1972 (1994).

Thus, section 1119 was designed to close a jurisdictional loophole — exposed by a murder that had been committed abroad by a private individual — to ensure the possibility of prosecuting U.S. nationals who murdered other U.S. nationals in certain foreign countries that lacked the ability to lawfully secure the perpetrator's appearance at trial. This loophole had nothing to do with the conduct of an authorized military operation by U.S. armed forces or the sort of CIA counterterrorism operation contemplated here. Indeed, prior to the enactment of section 1119, the only federal statute expressly making it a crime to kill U.S. nationals abroad, at least outside the special and maritime jurisdiction of the United States, reflected what appears to have been a particular concern with protection of Americans from terrorist attacks' See 18 U.S.C. § 2332(a), (d) (criminalizing unlawful killings of U.S. nationals abroad where the Attorney General or his subordinate certifies that the "offense was intended to coerce, intimidate, or retaliate against a government or a civilian population").23 It therefore would be anomalous to now read section 1119's closing of a limited jurisdictional gap as having been intended to jettison important applications of the established public authority justification, particularly in light of the statute's incorporation of substantive offenses codified in statutory provisions that from all indications were intended to incorporate recognized justifications and excuses.

It is true that here the target of the contemplated operations would be a U.S. citizen. But we do not believe al-Aulaqi's citizenship provides a basis for concluding that section 1119 would fail to incorporate the established public authority justification for a killing in this case. As we have explained, section 1119 incorporates the federal murder and manslaughter statutes, and thus its prohibition extends only to "unlawful" killings, 18 U.S.C. §§ 1111, 1112, a category that was intended to include, from all of the evidence of legislative intent we can find, only those killings that may not be permissible in light of traditional justifications for such action. At the time the predecessor versions of sections 1111 and 1112 were enacted, it was understood that killings undertaken in accord with the public authority justification were not "unlawful" because they were justified. There is no indication that, because section 1119(b) proscribes the unlawful killing abroad of U.S. nationals by U.S. nationals, it silently incorporated all justifications for killings except that public authority justification.

III.

Given that section 1119 incorporates the public authority justification, we must next analyze whether the contemplated DoD and CIA operations would be encompassed by that justification. In particular, we must analyze whether that justification would apply even though the target of the contemplated operations is a United States citizen. We conclude that it would — a conclusion that depends in part on our determination that each operation would accord with any potential constitutional protections of the United States citizen in these circumstances (see infra part VI). In reaching this conclusion, we do not address other cases or circumstances, involving different facts. Instead, we emphasize the sufficiency of the facts that have been represented to us here, without determining whether such facts would be necessary to the conclusion we reach.24

A.

We begin with the contemplated DoD operation. We need not attempt here to identify the minimum conditions that might establish a public authority justification for that operation. In light of the combination of circumstances that we understand would be present, and which we describe below, we conclude that the justification would be available because the operation would constitute the "lawful conduct of war" — a well-established variant of the public authority justification.25

As one authority has explained by example, "if a soldier intentionally kills an enemy combatant in time of war and within the rules of warfare, he is not guilty of murder," whereas, for example, if that soldier intentionally kills a prisoner of war — a violation of the laws of war — "then he commits murder." 2 LaFave, Substantive Criminal Law § 10.2(c), at 136; see also State v. Gut, 13 Minn. 341, 357 (1868) ("That it is legal to kill an alien enemy in the heat and exercise of war, is undeniable; but to kill such an enemy after he laid down his arms, and especially when he is confined in prison, is murder."); Perkins & Boyce, Criminal Law at 1093 ("Even in time of war an alien enemy may not be killed needlessly after he has been disarmed and securely imprisoned").26 Moreover, without invoking the public authority justification by terms, our Office has relied on the same notion in an opinion addressing the intended scope of a federal criminal statute that concerned the use of possibly lethal force. See United States Assistance to Countries that Shoot Down Civil Aircraft Involved in Drug Trafficking, 18 Op. O.L.C. 148, 164 (1994) ("Shoot Down Opinion") (concluding that the Aircraft Sabotage Act of 1984, 18 U.S.C. § 32(b)(2), which prohibits the willful destruction of a civil aircraft and otherwise applies to U.S. government conduct, should not be construed to have "the surprising and almost certainly unintended effect of criminalizing actions by military personnel that are lawful under international law and the laws of armed conflict").

In applying this variant of the public authority justification to the contemplated DoD operation, we note as an initial matter that DoD would undertake the operation pursuant to Executive war powers that Congress has expressly authorized. See Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 635, 72 S.Ct. 863, 96 L.Ed. 1153 (1952) (Jackson, J., concurring) ("When the President acts pursuant to an express or implied authorization of Congress, his authority is at its maximum, for it includes all that he possesses in his own right plus all that Congress can delegate."). By authorizing the use of force against "organizations" that planned, authorized, and committed the September 11th attacks, Congress clearly authorized the President's use of "necessary and appropriate" force against al-Qaida forces, because al-Qaida carried out the September 11th attacks. See Authorization for Use of Military Force ("AUMF"), Pub.L. No. 107-40, 115 Stat. 224, § 2(a) (2001) (providing that the President may "use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations, or persons.").27 And, as we have explained, supra at 9, a decision-maker could reasonably conclude that this leader of AQAP forces is part of al-Qaida forces. Alternatively, and as we have further explained, supra at 10 n. 5, the AUMF applies with respect to forces "associated with" al-Qaida that are engaged in hostilities against the U.S. or its coalition partners, and a decision-maker could reasonably conclude that the AQAP forces of which al-Aulaqi is a leader are "associated with" al Qaida forces for purposes of the AUMF. On either view, DoD would carry out its contemplated operation against a leader of an organization that is within the scope of the AUMF, and therefore DoD would in that respect be operating in accord with a grant of statutory authority.

Based upon the facts represented to us, moreover, the target of the contemplated operation has engaged in conduct as part of that organization that brings him within the scope of the AUMF. High-level government officials have concluded, on the basis of al-Aulaqi's activities in Yemen, that al-Aulaqi is a leader of AQAP whose activities in Yemen pose a "continued and imminent threat" of violence to United States persons and interests. Indeed, the facts represented to us indicate that al-Aulaqi has been involved, through his operational and leadership roles within AQAP, in an abortive attack within the United States and continues to plot attacks intended to kill Americans from his base of operations in Yemen. The contemplated DoD operation, therefore, would be carried out against someone who is within the core of individuals against whom Congress has authorized the use of necessary and appropriate force.28

Al-Aulaqi is a United States citizen, however, and so we must also consider whether his citizenship precludes the AUMF from serving as the source of lawful authority for the contemplated DoD operation. There is no precedent directly addressing the question in circumstances such as those present here; but the Supreme Court has recognized that, because military detention of enemy forces is "by `universal agreement and practice,' [an] `important incident[] of war,'" Hamdi v. Rumsfeld, 542 U.S. 507, 518, 124 S.Ct. 2633, 159 L.Ed.2d 578 (2004) (plurality opinion) (quoting Ex parte Quirin, 317 U.S. 1, 28, 30, 63 S.Ct. 2, 87 L.Ed. 3 (1942)), the AUMF authorized the President to detain a member of Taliban forces who was captured abroad in an armed conflict against the United States on a traditional battlefield. See id. at 517-19, 124 S.Ct. 2633 (plurality opinion).29 In addition, the Court held in Hamdi that this authorization applied even though the Taliban member in question was a U.S. citizen. Id. at 519-24, 124 S.Ct. 2633; see also Quirin, 317 U.S. at 37-38, 63 S.Ct. 2 ("[c]itizens who associate themselves with the military arm of the enemy government, and with its aid, guidance and direction enter [the United States] bent on hostile acts," may be treated as "enemy belligerents" under the law of war). Furthermore, lower federal courts have relied upon Hamdi to conclude that the AUMF authorizes DoD to detain individuals who are part of al-Qaida even if they are apprehended and transferred to U.S. custody while not on a traditional battlefield. See, e.g., Bensayah v. Obama, 610 F.3d 718, 720-21, 724-25, 727 (D.C.Cir. June 28, 2010) (concluding that the Department of Defense could detain an individual turned over to the U.S. in Bosnia if it demonstrates he was part of al-Qaida); Al-Adahi v. Obama, 613 F.3d 1102 (D.C.Cir.2010) (DoD has authority under AUMF to detain individual apprehended by Pakistani authorities in Pakistan and then transferred to U.S.); Anam v. Obama, 696 F.Supp.2d 1 (D.D.C.2010) (same); Razak Ali v. Obama, 2009 WL 4030864 (D.D.C.2009) (same); Sliti v. Bush, 592 F.Supp.2d 46 (D.D.C.2008) (same).

In light of these precedents, we believe the AUMF's authority to use lethal force abroad also may apply in appropriate circumstances to a United States citizen who is part of the forces of an enemy organization within the scope of the force authorization. The use of lethal force against such enemy forces, like military detention, is an "`important incident of war,'" Hamdi, 542 U.S. at 518, 124 S.Ct. 2633 (plurality opinion) (quotation omitted). See, e.g., General Orders No. 100: Instructions for the Government of Armies of the Untied States in the Field 15 (Apr. 24, 1863) (the "Lieber Code") ("[m]ilitary necessity admits of all direct destruction of life or limb of armed enemies"); International Committee of the Red Cross, Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 Aug. 1999 and Relating to the Protection of Victims of Non-International Armed Conflicts (Additional Protocol II) § 4789 (1987); Yoram Dinstein, The Conduct of Hostilities Under the Law of International Armed Conflict 94 (2004) ("Conduct of Hostilities") ("When a person takes up arms or merely dons a uniform as a member of the armed forces, he automatically exposes himself to enemy attack."). And thus, just as the AUMF authorizes the military detention of a U.S. citizen captured abroad who is part of an armed force within the scope of the AUMF, it also authorizes the use of "necessary and appropriate" lethal force against a U.S. citizen who has joined such an armed force. Moreover, as we explain further in Part VI, DoD would conduct the operation in a manner that would not violate any possible constitutional protections that al-Aulaqi enjoys by reason of his citizenship. Accordingly, we do not believe al-Aulaqi's citizenship provides a basis for concluding that he is immune from a use of force abroad that the AUMF otherwise authorizes.

In determining whether the contemplated DoD operation would constitute the "lawful conduct of war," LaFave, Substantive Criminal Law § 10.2(c), at 136, we next consider whether that operation would comply with the international law rules to which it would be subject — a question that also bears on whether the operation would be authorized by the AUMF. See Response for Petition for Rehearing and Rehearing En Banc, Al Bihani v. Obama, No. 09-5051 at 7 (D.C.Cir. May 13, 2010) (AUMF "should be construed, if possible, as consistent with international law") (citing Murray v. Schooner Charming Betsy, 6 U.S. (2 Cranch) 64, 118, 2 L.Ed. 208 (1804) ("an act of Congress ought never to be construed to violate the law of nations, if any other possible construction remains")); see also F. Hoffman-La Roche Ltd. v. Empagran S.A., 542 U.S. 155, 164, 124 S.Ct. 2359, 159 L.Ed.2d 226 (2004) (customary international law is "law that (we must assume) Congress ordinarily seeks to follow"). Based on the combination of facts presented to us, we conclude that DoD would carry out its operation as part of the non-international armed conflict between the United States and al-Qaida, and thus that on those facts the operation would comply with international law so long as DoD would conduct it in accord with the applicable laws of war that govern targeting in such a conflict.

In Hamdan v. Rumsfeld, the Supreme Court held that the United States is engaged in a non-international armed conflict with al-Qaida. 548 U.S. 557, 628-31, 126 S.Ct. 2749, 165 L.Ed.2d 723 (2006). In so holding, the Court rejected the argument that non-international armed conflicts are limited to civil wars and other internal conflicts between a state and an internal non-state armed group that are confined to the territory of the state itself; it held instead that a conflict between a transnational non-state actor and a nation, occurring outside that nation's territory, is an armed conflict "not of an international character" (quoting Common Article 3 of the Geneva Conventions) because it is not a "clash between nations." Id. at 630, 126 S.Ct. 2749.

Here, unlike in Hamdan, the contemplated DoD operation would occur in Yemen, a location that is far from the most active theater of combat between the United States and al-Qaida. That does not affect our conclusion, however, that the combination of facts present here would make the DoD operation in Yemen part of the non-international aimed conflict with al-Qaida.30 To be sure, Hamdan did not directly address the geographic scope of the noninternational armed conflict between the United States and al-Qaida that the Court recognized, other than to implicitly hold that it extended to Afghanistan, where Hamdan was apprehended. See 548 U.S. at 566, 126 S.Ct. 2749; see also id. at 641-42, 126 S.Ct. 2749 (Kennedy, J., concurring in part) (referring to Common Article 3 as "applicable to our Nation's armed conflict with al-Qaeda in Afghanistan"). The Court did, however, specifically reject the argument that non-international armed conflicts are necessarily limited to internal conflicts. The Common Article 3 term "conflict not of an international character," the Court explained, bears its "literal meaning" — namely, that it is a conflict that "does not involve a clash between nations." Id. at 630, 126 S.Ct. 2749 (majority opinion). The Court referenced the statement in the 1949 ICRC Commentary on the Additional Protocols to the Geneva Conventions that a non-international armed conflict "`is distinct from an international armed conflict because of the legal status of the entities opposing each other,'" id. at 631, 126 S.Ct. 2749 (emphasis added). The Court explained that this interpretation — that the nature of the conflict depends at least in part on the status of the parties, rather than simply on the locations in which they fight — in turn accords with the view expressed in the commentaries to the Geneva Conventions that "the scope of application" of Common Article 3, which establishes basic protections that govern conflicts not of an international character, "must be as wide as possible." Id.31

Invoking the principle that for purposes of international law an armed conflict generally exists only when there is "protracted armed violence between governmental authorities and armed groups," Decision on the Defence Motion for Interlocutory Appeal on Jurisdiction, Prosecutor v. Tadic, Case No. IT-94-1AR72, ¶ 70 (ICTY App. Chamber Oct. 2, 1995) ("Tadic Jurisdictional Decision"), some commentators have suggested that the conflict between the United States and al-Qaida cannot extend to nations outside Afghanistan in which the level of hostilities is less intense or prolonged than in Afghanistan itself. See, e.g., Mary Ellen O'Connell, Combatants and the Combat Zone, 43 U. Rich. L.Rev. 845, 857-59 (2009); see also Philip Alston, Report of the Special Rapporteur on extrajudicial, summary or arbitrary executions ¶ 54, at 18 (United Nations Human Rights Council, Fourteenth Session, Agenda Item 3, May 28, 2010) (acknowledging that a non-international armed conflict can be transnational and "often does" exist "across State borders," but explaining that the duration and intensity of attacks in a particular nation is also among the "cumulative factors that must be considered for the objective existence of an armed conflict"). There is little judicial or other authoritative, precedent that speaks directly to the question of the geographic scope of a non-international armed conflict in which one of the parties is a transnational, non-state actor and where the principal theater of operations is not within the territory of the nation that is a party to the conflict. Thus, in considering this issue, we must look to principles and statements from analogous contexts, recognizing that they were articulated without consideration of the particular factual circumstances of the sort of conflict at issue here.

In looking for such guidance, we have not come across any authority for the proposition that when one of the parties to an armed conflict plans and executes operations from a base in a new nation, an operation to engage the enemy in that location can never be part of the original armed conflict — and thus subject to the laws of war governing that conflict — unless and until the hostilities become sufficiently intensive and protracted within that new location. That does not appear to be the rule, or the historical practice, for instance, in a traditional international conflict. See John R. Stevenson, Legal Adviser, Department of State, United States Military Action in Cambodia. Questions of International Law (address before the Harnrnarskjold Forum of the Association of the Bar of the City of New York, May 28, 1970), in 3 The Vietnam War and International Law: The Widening Context 23, 28-30 (Richard A. Falk, ed.1972) (arguing that in an international armed conflict, if a neutral state has been unable for any reason to prevent violations of its neutrality by the troops of one belligerent using its territory as a base of operations, the other belligerent has historically been justified in attacking those enemy forces in that state). Nor do we see any obvious reason why that more categorical, nation-specific rule should govern in analogous circumstances in this sort of non-international armed conflict.32 Rather, we think the determination of whether a particular operation would be part of an ongoing armed conflict for purposes of international law requires consideration of the particular facts and circumstances present in each case. Such an inquiry may be particularly appropriate in a conflict of the sort here, given that the parties to it include transnational non-state organizations that are dispersed and that thus may have no single site serving as their base of operations.33

We also find some support for this view in an argument the United States made to the International Criminal Tribunal for Yugoslavia (ICTY) in 1995. To be sure, the United States was there confronting a question, and a conflict, quite distinct from those we address here. Nonetheless, in that case the United States argued that in determining which body of humanitarian law applies in a particular conflict, "the conflict must be considered as a whole," and that "it is artificial and improper to attempt to divide it into isolated segments, either geographically or chronologically, in an attempt to exclude the application of [the relevant] rules." Submission of the Government of the United States of America Concerning Certain Arguments Made by Counsel for the Accused in the Case of The Prosecutor of the Tribunal v. Dusan Tadic, Case No. IT-94-1AR72 (ICTY App. Chamber) at 27-28 (July 1995) ("U.S. Tadic Submission"). Likewise, the court in Tadic — although not addressing a conflict that was transnational in the way the U.S. conflict with al-Qaida is — also concluded that although "the definition of `armed conflict' varies depending on whether the hostilities are international or internal ... the scope of both internal and international armed conflicts extends beyond the exact time and place of hostilities." Tadic Jurisdictional Decision ¶ 67 (emphasis added); see also International Committee of the Red Cross, International Humanitarian Law and the Challenges of Contemporary Armed Conflicts 18 (2003) (asserting that in order to assess whether an armed conflict exists it is necessary to determine "whether the totality of the violence taking place between states and transnational networks can be deemed to be armed conflict in the legal sense"). Although the basic approach that the United States proposed in Tadic, and that the ICTY may be understood to have endorsed, was advanced without the current conflict between the U.S. and al-Qaida in view, that approach reflected a concern with ensuring that the laws of war, and the limitations on the use of force they establish, should be given an appropriate application.34 And that same consideration, reflected in Hamdan itself; see supra at 24, suggests a further reason for skepticism about an approach that would categorically deny that an operation is part of an armed conflict absent a specified level and intensity of hostilities in the particular location where it occurs.

For present purposes, in applying the more context-specific approach to determining whether an operation would take place within the scope of a particular armed conflict, it is sufficient that the facts as they have been represented to us here, in combination, support the judgment that DoD's operation in Yemen would be conducted as part of the non-international armed conflict between the United States and al-Qaida. Specifically, DoD proposes to target a leader of AQAP, an organized enemy force35 that is either a component of al-Qaida or that is a co-belligerent of that central party to the conflict and engaged in hostilities against the United States as part of the same comprehensive armed conflict, in league with the principal enemy. See supra at 9-10 & n. 5. Moreover, DoD would conduct the operation in Yemen, where, according to-the facts related to us, AQAP has a significant and organized presence, and from which AQAP is conducting terrorist training in an organized manner and has executed and is planning to execute attacks against the United States. Finally, the targeted individual himself, on behalf of that force, is continuously planning attacks from that Yemeni base of operations against the United States, as the conflict with al-Qaida continues. See supra at 7-9. Taken together, these facts support the conclusion that the DoD operation would be part of the non-international armed conflict the Court recognized in Hamdan.36

There remains the question whether DoD would conduct its operation in accord with the rules governing targeting in a non-international armed conflict — namely, international humanitarian law, commonly known as the laws of war. See Dinstein, Conduct of Hostilities at 17 (international humanitarian law "takes a middle road, allowing belligerent States much leeway (in keeping with the demands of military necessity) and yet circumscribing their freedom of action (in the name of humanitarianism")).37 The 1949 Geneva Conventions to which the United States is a party do not themselves directly impose extensive restrictions on the conduct of a noninternational armed conflict — with the principal exception of Common Article 3, see Hamdan, 548 U.S. at 630-31, 126 S.Ct. 2749. But the norms specifically described in those treaties "are not exclusive, and the laws and customs of war also impose limitations on the conduct of participants in non-international armed conflict." U.S. Tadic Submission at 33 n. 53; see also, e.g., Convention Respecting the Laws and Customs of War on Land, Oct. 18, 1907, Preamble ("Hague Convention (IV)"), 36 Stat. 2277, 2280 (in cases "not included" under the treaty, "the inhabitants and the belligerents remain under the protection and the rule of the principles of the law of nations, as they result from the usages among civilized peoples, from the laws of humanity, and the dictates of the public conscience").

In particular, the "fundamental rules" and "intransgressible principles of international customary law," Advisory Opinion of 8 July 1996 on the Legality of the Threat or Use of Nuclear Weapons IT 79, 1996 I.C.J. 226, 257 ("Nuclear Weapons Advisory Opinion"), which apply to all armed conflicts, include the "four fundamental principles that are inherent to all targeting decisions" — namely, military necessity, humanity (the avoidance of unnecessary suffering), proportionality, and distinction. United States Air Force, Targeting, Air Force Doctrine Document 2-1.9, at 88 (June 8, 2006); see also generally id. at 88-92; Dinstein, Conduct of Hostilities at 16-20, 115-16, 119-23. Such fundamental rules also include those listed in the annex to the Fourth Hague Convention, see Nuclear Weapons Advisory Opinion ¶ 80, at 258, article 23 of which makes it "especially forbidden" to, inter alia, kill or wound treacherously, refuse, surrender, declare a denial of quarter, or cause unnecessary suffering, 36 Stat. at 2301-02.

DoD represents that it would conduct its operation against al-Aulaqi in compliance with these fundamental law-of-war norms. See Chairman of the Joint Chiefs of Staff, Instruction 5810.01D, Implementation of the DoD Law of War Program ¶ 14.a, at 1 (Apr. 30, 2010) ("It is DOD policy that ... [m]embers of the DOD Components comply with the law of war during all armed conflicts, however such conflicts are characterized, and in all other military operations."). In particular, the targeted nature of the operation would help to ensure that it would comply with the principle of distinction, and DoD has represented to us that it would make every effort to minimize civilian casualties and that the officer who launches the ordnance would be required to abort a strike if he or she concludes that civilian casualties will be disproportionate or that such a strike will in any other respect violate the laws of war. See DoD May 18 Memorandum for OLC, at 1 ("Any official in the chain of command has the authority and duty to abort" a strike "if he or she concludes that civilian casualties will be disproportionate or that such a strike will otherwise violate the laws of war.").

Moreover, although DoD would specifically target al-Aularli, and would do so without advance warning, such characteristics of the contemplated operation would not violate the laws of war and, in particular, would not cause the operation to violate the prohibitions on treachery and perfidy — which are addressed to conduct involving a breach of confidence by the assailant. See, e.g., Hague Convention IV, Annex, art. 23(b), 36 Stat. at 2301-02 ("[I]t is especially forbidden ... to kill or wound treacherously individuals belonging to the hostile nation or army"); cf. also Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Aimed Conflicts, art. 37(1) (prohibiting the killing, injuring or capture of an adversary in an international armed conflict by resort to acts "inviting the confidence of [the] adversary ... with intent to betray that confidence," including feigning a desire to negotiate under truce or flag of surrender; feigning incapacitation; and feigning noncombatant status).38 Those prohibitions do not categorically preclude the use of stealth or surprise, nor forbid military attacks on identified, individual soldiers or officers, see U.S. Army Field Manual 27-10, 31 (1956) (article 23(b) of the Annex to the Hague Convention IV does not "preclude attacks on individual soldiers or officers of the enemy whether in the zone of hostilities, occupied territory, or else-where"), and we are not aware of any other law-of-war grounds precluding the use of such tactics. See Dinstein, Conduct of Hostilities at 94-95, 199; Abraham D. Sofaer, Terrorism, The Law, and the National Defense, 126 Mil. L.Rev. 89, 120-21 (1989).39 Relatedly, "there is no prohibition under the laws of war on the use of technologically advanced weapons systems in armed conflict — such as pilotless aircraft or so-called smart bombs — as long as they are employed in conformity with applicable laws of war." Koh, The Obama Administration and International, Law. DOD also informs us that if al-Aulaqi offers to surrender, DoD would accept such an offer.40

In light of all these circumstances, we believe DoD's contemplated operation against al-Aulaqi would comply with international law, including the laws of war applicable to this armed conflict, and would fall within Congress's authorization to use "necessary and appropriate force" against al-Qaida. In consequence, the operation should be understood to constitute the lawful conduct of war and thus to be encompassed by the public authority justification. Accordingly, the contemplated attack, if conducted by DoD in the mariner described, would not result in an "unlawful" killing and thus would not violate section 1119(b).

B.

We next consider whether the CIA's contemplated operation against al-Aulaqi in Yemen would be covered by the public authority justification. We conclude that it would be; and thus that operation, too, would not result in an "unlawful" killing prohibited by section 1119. As with our analysis of the contemplated DoD operation, we rely on the sufficiency of the particular factual circumstances of the CIA operation as they have been represented to us, without determining that the presence of those specific circumstances would be necessary to the conclusion we reach.

We explain in Part VI why the Constitution would impose no bar to the CIA's contemplated operation under these circumstances, based on the facts as they have been represented to us. There thus remains the question whether that operation would violate any statutory restrictions, which in turn requires us to consider whether 18 U.S.C. § 1119 would apply to the contemplated CIA operation.42 Based on the combination of circumstances that we understand would be present, we conclude that the public authority justification that section 1119 incorporates — and that would prevent the contemplated DoD operation from violating section 1119(b) — would also encompass the contemplated CIA operation.43

Specifically, we understand that the CIA, like DoD, would carry out the attack against an operational leader of an enemiforce, as Dart of the United States's ongoing non-international armed conflict with al-Qaida.

[redacted] the CIA — would conduct the operation in a manner that accords with the rules of international humanitarian law governing this armed conflict, and in circumstances See supra at 10-11.44

Nothing in the text or legislative history of section 1119 indicates that Congress intended to criminalize such an operation. Section 1119 incorporates the traditional public authority justification, and did not impose any special limitation on the scope of that justification. As we have explained, supra at 17-19, the legislative history of that criminal prohibition revealed Congress's intent to close a jurisdictional loophole that would have hindered prosecutions of murders carried out by private persons abroad. It offers no indication that Congress intended to prohibit the targeting of an enemy leader during an armed conflict in a mariner that would accord with the laws of war when performed by a duly authorized government agency. Nor does it indicate that Congress, in closing the identified loophole, meant to place a limitation on the CIA that would not apply to DoD.

Thus, we conclude that just as Congress did not intend section 1119 to bar the particular attack that DoD contemplates, neither did it intend to prohibit a virtually identical attack on the same target, in the same authorized conflict and in similar compliance with the laws of war, that the CIA would carry out in accord with [redacted]45

See also infra at 38-41 (explaining that the CIA operation under the circumstances described to us would comply with constitutional due process and the Fourth Amendment's "reasonableness" test for the use of deadly force).

Accordingly, we conclude that, just as the combination of circumstances present here supports the judgment that the public authority justification would apply to the contemplated operation by the armed forces, the combination of circumstances also supports the judgment that the CIA's operation, too, would be encompassed by that justification. The CIA's contemplated operation, therefore, would not result in an "unlawful" killing under section 1111 and thus would not violate section 1119.

IV.

For similar reasons, we conclude that the contemplated DoD and CIA operations would not violate another federal criminal statute dealing with "murder" abroad, 18 U.S.C. § 956(a). That law makes it a crime to conspire within the jurisdiction of the United States "to commit at any place outside the United States an act that would constitute the offense of murder, kidnapping, or maiming if committed in the special maritime and territorial jurisdiction of the United States" if any conspirator acts within the United States to effect any object of the conspiracy.[redacted]46

Like section 1119(b), section 956(a) incorporates by reference the understanding of "murder" in section 1111 of title 18. For reasons we explained earlier in this opinion, see supra at 12-14, section 956(a) thus incorporates the traditional public authority justification that section 1111 recognizes. As we have further explained both the CIA and DoD operations, on the facts as they have been represented to us, would be covered by that justification. Nor do we believe that Congress's reference in section 956(a) to "the special maritime and territorial jurisdiction of the United States" reflects an intent to transform such a killing into a "murder" in these circumstances — notwithstanding that our analysis of the applicability of the public authority justification is limited for present purposes to operations conducted abroad. A contrary conclusion would require attributing to Congress the surprising intention of criminalizing through section 956(a) an otherwise lawful killing of an enemy leader that another statute specifically prohibiting the murder of U.S. nationals abroad does not prohibit.

The legislative history of section 956(a) further confirms our conclusion that that statute should not be so construed. When the provision was first introduced in the Senate in 1995, its sponsors addressed and rejected the notion that the conspiracy prohibited by that section would apply to "duly authorized" actions undertaken on behalf of the federal government. Senator Biden introduced the provision at the behest of the President, as part of a larger package of anti-terrorism legislation. See 141 Cong. Rec. 4491 (1995) (statement of Sen. Biden). He explained that the provision was designed to "MO a void in the law," because section 956 at the time prohibited only U.S.-based conspiracies to commit certain property crimes abroad, and did not address crimes against persons. Id. at 4506. The amendment was designed to cover an offense "committed by terrorists" and was "intended to ensure that the government is able to punish those persons who use the United States as a base in which to plot such a crime to be carried out outside the jurisdiction of the United States." Id. Notably, the sponsors of the new legislation deliberately declined to place the new offense either within chapter 19 of title 18, which is devoted to "Conspiracy," or within chapter 51, which collects "Homicide" offenses (including those established in sections 1111, 1112, 1113 and 1119). Instead, as Senator Biden explained, "[s]ection 956 is contained in chapter 45 of title 18, United States Code, relating to interference with the foreign relations of the United States," and thus was intended to "cover[] those individuals who, without appropriate governmental authorization, engage in prohibited conduct that is harmful to the foreign relations of the United States." Id. at 4507. Because, as Senator Biden explained, the provision was designed, like other provisions of chapter 45, to prevent private interference with U.S. foreign relations, "[i]t is not intended to apply to duly authorized actions undertaken on behalf of the United States Government." Id.; see also 8 Op. O.L.C. 58 (1984) (concluding that section 5 of the Neutrality Act, 18 U.S.C. § 960, which is also in chapter 45 and which forbids the planning of, or participation in, military or naval expeditions to be carried on from the United States against a foreign state with which the United States is at peace, prohibits only persons acting in their private capacity from engaging in such conduct, and does not proscribe activities undertaken by government officials acting within the course and scope of their duties as United States officers). Senator Daschle expressed this same understanding when he introduced the identical provision in a different version of the anti-terrorism legislation a few months later. See 141 Cong. Rec. 11,960 (1995) (statement of Sen. Daschle). Congress enacted the new section 956(a) the following year, as part of the Antiterrorism and Effective Death Penalty Act, Pub.L. No. 104-132, tit. VII, § 704(a), 110 Stat. 1214, 1294-95 (1996). As far as we have been able to determine, the legislative history contains nothing to contradict the construction of.section 956(a) described by Senators Biden and Daschle.

Accordingly, we do not believe section 956(a) would prohibit the contemplated operations.

V.

We next consider the potential application of the War Crimes Act, 18 U.S.C. § 2441, which makes it a federal crime for a member of the Aimed Forces or a national of the United States to "commit[] a war crime." Id. § 2441(a). Subsection 2441(c) defines a "war crime" for purposes of the statute to mean any conduct (i) that is defined as a grave breach in any of the Geneva Conventions (or any Geneva protocol to which the U.S. is a party); (ii) that is prohibited by four specified articles of the Fourth Hague Convention of 1907; (iii) that is a "grave breach" of Common Article 3 of the Geneva Conventions (as defined elsewhere in section 2441) when committed "in the context of and in association with an armed conflict not of an international character"; or (iv) that is a willful killing or infliction of serious injury in violation of the 1996 Protocol on Prohibitions or Restrictions on the Use of Mines, Booby-Traps and Other Devices. Of these, the only subsection potentially applicable here is that dealing with Common Article 3 of the Geneva Conventions.47

In defining what conduct constitutes a "grave breach" of Common Article 3 for purposes of the War Crimes Act, subsection 2441(d) includes "murder," described in pertinent part as "[t]he act of a person who intentionally kills, or conspires or attempts to kill ... one or more persons taking no active part in the hostilities, including those placed out of combat by sickness, wounds, detention, or any other cause." 18 U.S.C. § 2441(d)(1)(D). This language derives from Common Article 3(1) itself, which prohibits certain acts (including murder) against "[p]ersons. taking no active part in the hostilities, including members of armed forces who have laid down their arms and those placed `hors de combat' by sickness, wounds, detention, or any other cause." See, e.g., Geneva Convention Relative to the Treatment of Prisoners of War, Aug. 12, 1949, [1955], art. 3(1), 6 U.S.T. 3316, 3318-20. Although Common Article 3 is most commonly applied with respect to persons within a belligerent party's control, such as detainees, the language of the article is not so limited — it protects all "[p]ersons taking no active part in the hostilities" in an armed conflict not of an international character.

Whatever might be the outer bounds of this category of covered persons, we do not think it could encompass al-Aulaqi. Common Article 3 does not alter the fundamental law-of-war principle concerning a belligerent party's right in an armed conflict to target individuals who are part of an enemy's aimed forces. See supra at 23. The language of Common Article 3 "makes clear that members of such armed forces [of both the state and non-state parties to the conflict] ... are considered as `taking no active part in the hostilities' only once they have disengaged from their fighting function (`have laid down their arms') or are placed hors de combat; mere suspension of combat is insufficient." International Committee of the Red Cross, Interpretive Guidance on the Notion of Direct Participation in Hostilities Under International Humanitarian Law 28 (2009); cf. also id. at 34 ("individuals whose continuous function involves the preparation, execution, or command of acts or operations amounting to direct participation in hostilities are assuming a continuous combat function," in which case they can be deemed to be members of a non-state armed group subject to continuous targeting); accord Gherebi v. Obama, 609 F.Supp.2d 43, 65 (D.D.C.2009) ("the fact that `members of armed forces who have laid down their arms and those placed hors de combat' are not `taking [an] active part in the hostilities' necessarily implies that `members of armed forces' who have not surrendered or been incapacitated are `taking [an] active part in the hostilities' simply by virtue of their membership in those armed forces"); id. at 67 ("Common Article 3 is not a suicide pact; it does not provide a free pass for the members of an enemy's armed forces to go to or fro as they please so long as, for example, shots are not fired, bombs are not exploded, and places are not hijacked"). Al-Aulaqi, an active, high-level leader of an enemy force who is continually involved in planning and recruiting for terrorist attacks, can on that basis fairly be said to be taking "an active part in hostilities." Accordingly, targeting him in the circumstances posited to us would not violate Common Article 3 and therefore would not violate the War Crimes Act.

VI.

We conclude with a discussion of potential constitutional limitations on the contemplated operations due to al-Aulaqi's status as a U.S. citizen, elaborating upon the reasoning in our earlier memorandum discussing that issue. Although we have explained above why we believe that neither the DoD or CIA operation would violate sections 1119(b), 956(a) and 2441 of title 18 of the U.S.Code, the fact that al-Aulaqi is a United States citizen could raise distinct questions under the Constitution. As we explained in our earlier memorandum, Barron Memorandum at 5-7, we do not believe that al-Aulaqi's U.S. citizenship imposes constitutional limitations that would preclude the contemplated lethal, action under the facts represented to us by DoD, the CIA and the Intelligence Community.

Because al-Aulaqi is a U.S. citizen, the Fifth Amendment's Due Process Clause, as well as the Fourth Amendment, likely protects him in some respects even while he is abroad. See Reid v. Covert, 354 U.S. 1, 5-6, 77 S.Ct. 1222, 1 L.Ed.2d 1148 (1957) (plurality opinion); United States v. Verdugo-Urquidez, 494 U.S. 259, 269-70, 110 S.Ct. 1056, 108 L.Ed.2d 222 (1990); see also In re Terrorist Bombings of U.S. Embassies in East Africa, 552 F.3d 157, 170 n. 7 (2d Cir.2008).

In Hamdi, a plurality of the Supreme Court used the Mathews v. Eldridge balancing test to analyze the Fifth Amendment due process rights of a U.S. citizen captured on the battlefield in Afghanistan and detained in the United States who wished to challenge the government's assertion that he was a part of enemy forces, explaining that "the process due in any given instance is determined by weighing `the private interest that will be affected by the official action' against the Government's asserted interest, `including the function involved' and the burdens the Government would face in providing greater process." 542 U.S. at 529, 124 S.Ct. 2633 (plurality opinion) (quoting Mathews v. Eldridge, 424 U.S. 319, 335, 96 S.Ct. 893, 47 L.Ed.2d 18 (1976)).

We believe similar reasoning supports the constitutionality of the contemplated operations here. As explained above, on the facts represented to us, a decision-maker could reasonably decide that the threat posed by al-Aulaqi's activities to United States persons is "continued" and "imminent"

In addition to the nature of the threat posed by al-Aulaqi's activities, both agencies here have represented that they intend to capture rather than target al-Aulaqi if feasible; yet we also understand that an operation by either agency to capture al-Aulaqi in Yemen would be infeasible at this time.

Cf., e.g., Public Committee Against Torture in Israel v. Government of Israel, HO 769/02 S 40, 46 L.L.M. 375, 394 (Israel Supreme Court sitting as the High Court of Justice, 2006) (although arrest, investigation and trial "might actually be particularly practical under the conditions of belligerent occupation, in which the army controls the area in which the operation takes place," such alternatives "are not means which can always be used," either because they are impossible or because they involve a great risk to the lives of soldiers).

Although in the "circumstances of war," as the Hamdi plurality observed, "the risk of erroneous deprivation of a citizen's liberty in the absence of sufficient process... is very real," 542 U.S. at 530, 124 S.Ct. 2633, the plurality also recognized that "the realities of combat" render certain uses of force "necessary and appropriate," including against U.S. citizens who have become part of enemy forces — and that "due process analysis need not blink at those realities," id. at 531, 124 S.Ct. 2633. we conclude that at least where, as here, the target's activities pose a "continued and imminent threat of violence or death" to U.S. persons, "the highest officers in the Intelligence Community have reviewed the factual basis" for the lethal operation, and a capture operation would be infeasible — and where the CIA and DoD "continue to monitor whether changed circumstances would permit such an alternative," see also DoD May 18 Memorandum for OLC at 2 — the "realities of combat" and the weight of the government's interest in using an authorized means of lethal force against this enemy are such that the Constitution would not require the government to provide further process to the U.S. person before using such force. Cf. Hamdi 542 U.S. at 535, 124 S.Ct. 2633 (noting that Court "accord[s] the greatest respect and consideration to the judgments of military authorities in matters relating to the actual prosecution of war, and ... the scope of that discretion necessarily is wide") (plurality opinion).

Similarly, assuming that the Fourth Amendment provides some protection to a U.S. person abroad who is part of al-Qaida and that the operations at issue here would result in a "seizure" within the meaning of that Amendment,

The Supreme Court has made clear that the constitutionality of a seizure is determined by "balanc[ing] the nature and quality of the intrusion on the individual's Fourth Amendment interests against the importance of the governmental interests alleged to justify the intrusion." Tennessee v. Garner, 471 U.S. 1, 8, 105 S.Ct. 1694, 85 L.Ed.2d 1 (1985) (internal quotation marks omitted); accord Scott v. Harris, 550 U.S. 372, 383, 127 S.Ct. 1769, 167 L.Ed.2d 686 (2007). Even in domestic law enforcement operations, the Court has noted that "[w]here the officer has probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others, it is not constitutionally unreasonable to prevent escape by using deadly force." Garner, 471 U.S. at 11, 105 S.Ct. 1694. Thus, "if the suspect threatens the officer with a weapon or there is probable cause to believe that he has committed a crime involving the infliction or threatened infliction of serious physical harm, deadly force may be used if necessary to prevent escape and if, where feasible, some warning has been given." Id. at 11-12, 105 S.Ct. 1694.

The Fourth Amendment "reasonableness" test is situation-dependent. Cf. Scott, 550 U.S. at 382, 127 S.Ct. 1769 (Garner "did not establish a magical on/off switch that triggers rigid preconditions whenever an officer's actions constitute `deadly force'"). What would constitute a reasonable use of lethal force for purposes of domestic law enforcement operations will be very different from what would be reasonable in a situation like such as that at issue here. In the present circumstances, as we understand the facts, the U.S. citizen in question has gone overseas and become part of the forces of an enemy with which the United States is engaged in an armed conflict; that person is engaged in continual planning and direction of attacks upon U.S. persons from one of the enemy's overseas bases of operations; the U.S. government does not know precisely when such attacks will occur; and a capture operation would be infeasible. at least where high-level government officials have determined that a capture operation overseas is infeasible and that the targeted person is part of a dangerous enemy force and is engaged in activities that pose a continued and imminent threat to U.S. persons or interests the use of lethal force would not violate the Fourth Amendment. and thus that the intrusion on any Fourth Amendment interests would be outweighed by "the importance of the governmental interests [that] justify the intrusion," Garner, 471 U.S. at 8, 105 S.Ct. 1694, based on the facts that have been represented to us.

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