FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,             
               Plaintiff-Appellant,
               v.                           No. 06-30192
W. R. GRACE; ALAN R. STRINGER;
HENRY A. ESCHENBACH; JACK W.                 D.C. No.
                                          CR-05-00007-DWM
WOLTER; WILLIAM J. MCCAIG;
                                              OPINION
ROBERT J. BETTACCHI; O. MARIO
FAVORITO; ROBERT C. WALSH,
            Defendants-Appellees.
                                      
      Appeal from the United States District Court
              for the District of Montana
    Donald W. Molloy, Chief District Judge, Presiding

             Argued and Submitted En Banc
         December 12, 2007—Pasadena, California

                    Filed May 15, 2008

   Before: Alex Kozinski, Chief Judge, Harry Pregerson,
         Stephen Reinhardt, Andrew J. Kleinfeld,
         Michael Daly Hawkins, Susan P. Graber,
     M. Margaret McKeown, Kim McLane Wardlaw,
 Raymond C. Fisher, Carlos T. Bea and Milan D. Smith, Jr.,
                     Circuit Judges.

                Opinion by Judge Fisher;
              Concurrence by Judge Hawkins




                           5633
5636           UNITED STATES v. W. R. GRACE


                        COUNSEL

James C. Kilbourne (argued), Kevin M. Cassidy and Allen M.
Brabender, Attorneys, United States Department of Justice,
Washington, District of Columbia; William W. Mercer,
United States Attorney; Kris A. McLean, Assistant United
States Attorney; Ronald J. Tenpas, Acting Assistant Attorney
General, for the plaintiff-appellant.

Christopher Landau, P.C. (argued), Laurence A. Urgenson,
Tyler D. Mace and Michael D. Shumsky, Kirkland & Ellis
LLP, Washington, District of Columbia; Stephen R. Brown,
Charles E. McNeil and Kathleen L. DeSoto, Garlington Lohn
& Robinson, PLLP, Missoula, Montana, for defendant-
appellee W. R. Grace & Co.

Ronald F. Waterman, Gough, Shanahan, Johnson & Water-
man, Helena, Montana; David S. Krakoff and Gary A. Win-
ters, Mayer Brown LLP, Washington, District of Columbia,
for defendant-appellee Henry A. Eschenbach.
                UNITED STATES v. W. R. GRACE              5637
Mike Milodragovich and W. Adam Duerk, Milodragovich,
Dale, Steinbrenner & Binney, Missoula, Montana; Jeremy
Maltby, O’Melveny & Myers LLP, Los Angeles, California,
for defendant-appellee Jack W. Wolter.

Palmer Hoovestal, Hoovestal Law Firm, PLLC, Helena, Mon-
tana; Elizabeth Van Doren Gray, Sowell, Gray, Stepp & Laf-
fitte, LLC, Columbia, South Carolina; William A. Coates,
Roe Cassidy Coates & Price, PA, Greenville, South Carolina,
for defendant-appellee William J. McCaig.

Brian Gallik, Goetz, Gallik & Baldwin, P.C., Bozeman, Mon-
tana; Thomas C. Frongillo, Weil, Gotshal & Manges LLP,
Boston, Massachusetts; Vernon S. Broderick, Weil, Gotshal
& Manges LLP, New York, New York, for defendant-
appellee Robert J. Bettacchi.

C.J. Johnson, Kalkstein Law Firm, Missoula, Montana; Ste-
phen A. Jonas and Robert Keefe, Wilmer Cutler Pickering
Hale and Dorr LLP, Boston, Massachusetts, for defendant-
appellee O. Mario Favorito.

Catherine A. Laughner and Aimee M. Grmoljez, Browning
Kaleczyc Berry & Hoven, P.C., Helena, Montana; Stephen R.
Spivack, Bradley Arant Rose & White LLP, Washington, Dis-
trict of Columbia; David E. Roth, Bradley Arant Rose &
White LLP, Birmingham, Alabama, for defendant-appellee
Robert C. Walsh.


                         OPINION

FISHER, Circuit Judge:

  We granted en banc review of this appeal by the govern-
ment, brought pursuant to 18 U.S.C. § 3731, to resolve two
questions. First, does a United States Attorney’s simple certi-
5638             UNITED STATES v. W. R. GRACE
fication under § 3731 that the government’s interlocutory
appeal in a pending criminal case is not taken for purpose of
delay and that the evidence the district court suppressed or
excluded is substantial proof of a fact material in the proceed-
ing suffice to establish our jurisdiction to hear the interlocu-
tory appeal? Second, if so, did the district court in this case
have the authority to order pretrial disclosure by the govern-
ment of its final list of witnesses and evidentiary documents
and to exclude witnesses and evidence not timely disclosed in
compliance with such orders?

   First, we hold that the United States Attorney’s bare certifi-
cation regarding delay and materiality in accordance with the
terms of § 3731 was sufficient to give us appellate jurisdiction
to address the government’s objections to the district court’s
orders. We therefore overrule our prior decisions to the extent
that they conflict with our ruling today, including United
States v. Loud Hawk, 

(9th Cir. 1979) (en banc),
and United States v. Adrian, 

(9th Cir. 1992).
Second, we hold that the district court did have the authority
to issue and enforce its pretrial orders compelling the govern-
ment to disclose its witness list and did not abuse its discre-
tion in doing so. We therefore also overrule United States v.
Hicks, 

(9th Cir. 1996), to the extent that it pur-
ported to deny the district court such authority.

                          OVERVIEW

   W.R. Grace & Co. mined and processed vermiculite ore
outside Libby, Montana, from the early 1960s until the early
1990s. On February 7, 2005, the United States indicted Grace
and several of its officers on numerous charges alleging that
they engaged in criminal acts during the course of Grace’s
mining operations, related to the improper disposal of
asbestos-contaminated vermiculite. The district court, recog-
nizing the magnitude of the case — with a relevant time
period spanning nearly 30 years and potentially more than a
thousand victims — held a pretrial case management confer-
                 UNITED STATES v. W. R. GRACE               5639
ence in March 2005 and thereafter entered a case management
order memorializing the results of the conference.

   The March 2005 order established a “firm” trial date of
September 11, 2006, and set forth a discovery schedule. In
pertinent part, the schedule required the government to pro-
duce “all discoverable materials specified in Fed. R. Crim. P.
16(a)” by April 29, 2005, “a preliminary list of its intended
witnesses and exhibits” by May 27, 2005, and a “finalized list
of witnesses and trial exhibits, including [a] finalized disclo-
sure of prosecution’s expert witnesses” by September 30,
2005. Moreover, to the extent that the parties intended to
engage expert witnesses at trial, the order required “full[ ]
compl[iance] with the requirements of Rule 16(a)(1)(E) and
Rule 16(b)(1)(C),” including that “expert reports . . . are com-
plete, comprehensive, accurate, and tailored to the issues on
which the expert is expected to testify.” The government did
not object to the district court’s order, and subsequently made
significant disclosures in compliance with it.

   On September 30, 2005, the government notified the dis-
trict court that it had produced for the defendants its “final
witness list and final exhibit list,” but stated that the govern-
ment “reserve[d] its right to update its witness list and exhibit
list through the close of all evidence at trial.” The govern-
ment’s disclosure included more than 230 witnesses.

   The defendants disputed the sufficiency of the govern-
ment’s disclosures. On November 23, 2005, the district court
issued three orders pursuant to Federal Rule of Criminal Pro-
cedure 16, chiding the government for its “impermissibly nar-
row view of the obligations under Brady” and clarifying the
materials the government was required to produce pursuant to
Rule 16.

   On December 2, 2005, the parties met with the district
court for a status conference. At this conference, the discus-
sion included the sufficiency of the prosecution’s expert dis-
5640             UNITED STATES v. W. R. GRACE
closures, its compliance with the previous discovery orders,
and the defendants’ concern about the growing size of the
government’s witness list. Shortly thereafter, the district court
entered an order on December 5, 2005 (“the December 2005
order”), limiting the government’s presentation of witnesses
at trial “to those witnesses that have been disclosed as of the
filing of this Order” and limiting the reports the government
experts may rely upon to those “contained in the discovery
produced to date or . . . currently subject to an order of this
Court requiring production.”

  In response to government objections, the court on Febru-
ary 17, 2006 clarified that, if necessary for rebuttal, the gov-
ernment could call unlisted witnesses and use other evidence.
The government then brought an interlocutory appeal under
18 U.S.C. § 3731, challenging the district court’s pretrial
orders — specifically the March 2005 case management order
and the court’s December 2005 and February 2006 enforce-
ment orders (collectively, the “enforcement orders”).

  Section 3731 provides in part:

       An appeal by the United States shall lie to a court
    of appeals from a decision or order of a district court
    suppressing or excluding evidence or requiring the
    return of seized property in a criminal proceeding,
    not made after the defendant has been put in jeop-
    ardy and before the verdict or finding on an indict-
    ment or information, if the United States attorney
    certifies to the district court that the appeal is not
    taken for purpose of delay and that the evidence is
    a substantial proof of a fact material in the proceed-
    ing.

(Emphasis added.) Here, the United States Attorney for the
District of Montana certified in the words of the statute that
the government’s interlocutory appeal “is not taken for pur-
pose of delay and that the evidence excluded by the district
                   UNITED STATES v. W. R. GRACE                      5641
court’s order described in [the] notice of appeal is substantial
proof of a fact material in the proceeding ongoing before the
district court.” The government contends that its unembel-
lished certification suffices to establish appellate jurisdiction.
On the merits of its appeal, the government challenges the
district court’s authority to require or enforce a finalized pre-
trial list of witnesses and trial exhibits, and argues that, even
if authorized, the enforcement orders were an abuse of the
court’s discretion. The defendants counter that the govern-
ment’s § 3731 certification did not adequately establish the
materiality of the excluded evidence,1 so we lack jurisdiction
to hear the government’s appeal; and, in any event, the district
court acted within its authority.

   Adhering to existing Ninth Circuit law, a three-judge panel
of this court declined to accept the government’s bare certifi-
cation that simply recited the language of § 3731, and
requested the parties to submit supplemental briefs discussing
whether the excluded evidence was in fact “substantial proof
of a fact material in the proceeding.” United States v. W.R.
Grace, 

, 1124 (9th Cir. 2007), reh’g en banc
granted, 

(9th Cir. 2007). After receiving more
specific information from the government about the nature
and relevance of the excluded evidence, the panel concluded
that the government’s proffer, albeit belated, had satisfied its
burden to demonstrate materiality under Loud 

(holding that the “government’s right to appeal” is
available only “conditionally”), and 

(the government must provide more than a “bare certification”
to establish appellate jurisdiction). On the merits of the
appeal, the panel affirmed the district court’s rulings with
respect to expert witnesses and related documents, but fol-
lowed Hicks and held that the district court exceeded its
authority in excluding from the government’s case-in-chief
undisclosed nonexpert witnesses.
  1
    The defendants do not challenge the government’s certification that the
interlocutory appeal is not taken for purposes of delay.
5642            UNITED STATES v. W. R. GRACE
  We agreed to rehear this case en banc to reexamine the pre-
cedents that governed the decision of the three-judge panel.

                             DISCUSSION

                  I.   Standard of Review

   “Jurisdiction is a question of law subject to de novo
review.” United States v. Neville, 

, 994 (9th Cir.
1993). We review de novo a district court’s rulings on the
scope of its authority to order discovery under Federal Rule
of Criminal Procedure 16. United States v. Mendoza-Paz, 

, 1111 (9th Cir. 2002).

                       II.    Section 3731

   Section 3731 grants the government the right to an interloc-
utory appeal from a district court’s evidentiary rulings in cer-
tain circumstances. We have previously explained that the
government’s “right (via § 3731) to appeal a district court’s
order suppressing evidence is conditional.” Loud 

; see 

-91. “First, the
appeal is not available if the defendant has been put in jeop-
ardy. Second, the appeal must not be taken for purpose of
delay. Third, the evidence suppressed must be substantial
proof of a fact material in the proceeding.” Loud 

. We have required that the government’s bare
certification be backed up by a preliminary showing that the
excluded evidence truly is material. See 

the materiality “condition must be met before appeal of the
suppression order can properly be taken”). In Adrian, we
defined materiality for purposes of § 3731 thus: “assuming
that the evidence would be admissible, a reasonable trier of
fact could find the evidence persuasive in establishing the
proposition for which the government seeks to admit 

.
                    UNITED STATES v. W. R. GRACE                      5643
   [1] The purposes of our certification-plus rule were salutary
— to assure that the government’s decision to involve us in
the trial process was a carefully considered judgment and to
provide us with enough information to determine whether a
time-consuming appeal was truly justified. Nonetheless, we
are now persuaded that the plain language of the statute shows
that Congress intended that, as long as the other requirements
of § 3731 are present, mere certification regarding the delay
and materiality prerequisites is all the statute requires to
invoke our appellate jurisdiction. This is evident from
§ 3731’s phrasing, “An appeal by the United States shall lie
to a court of appeals . . . if the United States attorney certifies
to the district court that the appeal is not taken for purpose of
delay and that the evidence is a substantial proof of a fact
material in the proceeding.” (Emphasis added.) We read Con-
gress as specifying what the government must do to establish
those jurisdictional preconditions. Nothing in the statute
requires the government to go further and prove that the evi-
dence suppressed or excluded by the district court is actually
material to the proceeding before our jurisdiction can attach.
Where congressional intent “has been expressed in reasonably
plain terms, that language must ordinarily be regarded as con-
clusive.” Griffin v. Oceanic Contractors, Inc., 

,
570 (1982) (internal quotation marks omitted). Moreover,
Congress specifically instructed us in § 3731 that its “provi-
sions . . . shall be liberally construed to effectuate its pur-
poses.” 18 U.S.C. § 3731. The purpose of § 3731 is to give
the government a window of opportunity to challenge a dis-
trict court’s exclusion of allegedly material evidence before
jeopardy attaches; we should not, therefore, read into the stat-
ute an unwritten additional hurdle, even if well intentioned.2
  2
    The concurrence looks to the Westfall Act, 28 U.S.C. § 2679(d)(1), as
a point of reference for interpreting § 3731. As the concurrence itself can-
didly concedes, however, given the contrast between the Westfall Act’s
certification regime and that of § 3731, the Act does not resolve our ulti-
mate inquiry. Concurring op. at 5665-66 & n.3. We are satisfied that
§ 3731 means what it says, a conclusion shared by our sister circuits. More
importantly, our reading does not require accepting the United States
Attorney’s certification as conclusive on the merits, only as sufficient to
trigger our jurisdiction to reach them.
5644               UNITED STATES v. W. R. GRACE
   [2] Accordingly, we now hold that a certification by a
United States Attorney (personally, not by an Assistant
United States Attorney) that the appeal is not taken for the
purpose of delay and that the evidence is substantial proof of
a fact material in the proceeding is sufficient for purposes of
establishing our jurisdiction under § 3731. The certification-
plus rule of Loud Hawk and its progeny is overruled. See
United States v. Gantt, 

, 998 (9th Cir. 1999);
United States v. Poulsen, 

, 1333-34 (9th Cir.
1994); 

-91; United States v. Layton,

, 554 (9th Cir. 1983).

   By so holding, we align ourselves with our sister circuits
that have held that § 3731 is satisfied as long as the United
States Attorney certifies that the statutory conditions are met.
See Gov’t of Virgin Is. v. Hodge, 

, 325 & n.13
(3d Cir. 2004) (holding that jurisdiction was proper based on
the filing of the certification); United States v. Centracchio,

, 813 (7th Cir. 2001) (“We therefore treat as con-
clusive of our jurisdiction over a [§ 3731] appeal the submis-
sion of the certification required by the statute.”); United
States v. Johnson, 

, 923 (8th Cir. 2000) (holding
that “appellate jurisdiction is proper if the government simply
certifies that the evidence suppressed is substantial proof of a
material fact”); see also United States v. McNeill, 

, 308-09 (4th Cir. 2007) (suggesting certification alone is
sufficient if timely).3 These holdings are all consistent with
§ 3731’s mandate that an interlocutory appeal “shall lie . . .
if” the United States Attorney makes the specified representa-
tions in his or her certification. Our former rule added a hur-
dle that had to be cleared before our jurisdiction could attach;
that is not what Congress instructed.
  3
    Two circuits — the Eighth and the Third — have expressly noted the
circuit split, in which the “Ninth Circuit, apparently alone, requires the
government to prove that the evidence suppressed by the district court is
actually ‘material’ to the upcoming trial.” 

; see

n.13.
                    UNITED STATES v. W. R. GRACE                       5645
   The concurring opinion raises two principal concerns based
on its fears of what might go wrong under the prevailing
certification-only rule we are adopting. First, it worries about
delays in the trial proceedings, to the disadvantage of defen-
dants. We acknowledge those concerns but do not believe that
they allow us to impose a two-step screening process that
Congress has not required. Section 3731 not only requires the
United States Attorney to certify that the interlocutory appeal
is not for purpose of delay, but also mandates that the appeal
“shall be taken within thirty days after the decision, judgment
or order has been rendered and shall be diligently prosecut-
ed.” We have the authority to assure that these affirmative
requirements are met.4 Moreover, we also have the ability to
expedite the appellate process should that become necessary
in an individual case, or even on a systemic basis if our expe-
rience warrants it. In that regard, we have no evidence that the
certification-plus rule of Loud Hawk is more efficient than
simply accepting certification as sufficient to establish our juris-
diction.5
  4
     For example, we have previously dealt with certificates that are not
timely filed in the district court. See, e.g., United States v. Becker, 

, 445 (9th Cir. 1991) (noting that whether the government could
supplement the record on appeal with an untimely filed § 3731 certifica-
tion was a discretionary matter for the court); see also 

(noting that although failure to timely file a § 3731 certification
does not deprive the court of jurisdiction over the appeal, the court had
discretion to impose any sanction necessary to enforce the requirement of
filing a § 3731 certification, including dismissal); United States v.
Romaszko, 

, 759-60 (2d Cir. 2001) (per curiam) (holding that
the late filing of a § 3731 certification does not preclude jurisdiction but
does permit the court to exercise its discretion under Federal Rule of
Appellate Procedure 3(a) to dismiss the appeal). The merits of whether the
government should ever be excused from failure to file a § 3731 certifica-
tion on a timely basis are not before us in this appeal.
   5
     The concurrence notes that “[i]t currently takes nine to ten months
from the filing of an interlocutory appeal in a criminal case to its place-
ment on an argument calendar.” Concurring op. at 5679-80. That may be,
although such is not the case when the proceedings are expedited. In any
event, Congress has made the judgment that the government is entitled to
5646               UNITED STATES v. W. R. GRACE
   Second, the concurrence urges that, by accepting the United
States Attorney’s certification as sufficient to invoke our
jurisdiction, we are “blindly trust[ing] United States Attor-
neys,” adopting a rule that “permits a prosecutor to disrupt
proceedings with the stroke of a pen” and giving the prosecu-
tion “unchecked authority to pursue interlocutory appeals
from all suppression orders.” Concurring op. at 5675, 5682,
5679. Not so. The certification itself is a representation by the
United States Attorney, as an officer of the court, that the
appeal is not for purposes of delay and that the suppressed
evidence is indeed material.6 As to materiality, § 3731 pro-
vides that the certification establishes only our jurisdiction. If
the merits of the appeal independently require us to question
whether the evidence truly is material, the government’s certi-
fication is not conclusive — as the concurrence acknowl-
edges, 

& n.10 — so we are not required to
“mak[e] new law in a near factual vacuum.” 

Moreover, should we find the government’s appeal to be
patently frivolous or have reason to believe its certification is
false, we could directly sanction such misconduct, surely a
potent “check” on prosecutorial abuse of the certification pro-
cess. In short, the certification-only rule that we adopt today

an interlocutory appeal in specified circumstances, and the Loud Hawk
certification-plus rule does nothing to get the appeal on an argument cal-
endar any faster than the prevailing certification-only rule. Indeed,
because we must first determine the jurisdictional issue and then deter-
mine the merits separately, a final determination under the Loud Hawk
rule may well take longer. Although the concurrence invokes the appeal
in this case to “demonstrate the Loud Hawk rule’s necessity” to prevent
delay, 

shows the opposite. But for Loud Hawk, the original
panel would not have had to look beyond the certification and spend time
forcing the government to prove the suppressed evidence was material (it
was) before getting to the merits of the appeal. (That “the trial date
remains in limbo,” 

is largely a function of our en banc pro-
cess.)
   6
     The definition of materiality governing the United States Attorney’s
certification is well established, see 

(quoted in
text, above), and remains the law of this circuit.
                UNITED STATES v. W. R. GRACE                  5647
and which is followed in other circuits does not give prosecu-
tors any benefit beyond the statutory right to the interlocutory
appeal that Congress provided in § 3731, or permit a United
States Attorney to misuse the certification process.

   In that regard, we emphasize that we are not diluting a stan-
dard implicit in the certification requirement. By specifying
that the United States Attorney must certify the appeal, Con-
gress plainly intended that the decision to take an interlocu-
tory appeal be a serious, considered judgment, not simply an
administrative formality. The Fourth Circuit recently empha-
sized this point:

      The authorization to file these interlocutory
    appeals is important to the prosecution of criminal
    cases because it permits the government to obtain
    appellate review, before jeopardy attaches, of trial
    court decisions suppressing what the government
    believes is evidence necessary to prove a crime. But
    because such an appeal necessarily disrupts trial
    court proceedings, the authorization contains an
    important limitation that is intended to protect defen-
    dants from undue delay . . .

       The certification requirement of § 3731 operates
    to ensure that before the United States interrupts a
    criminal proceeding (and thereby delays a defendant
    from obtaining resolution of the charges against him)
    by taking an interlocutory appeal, it has evaluated
    whether the appeal is warranted.

       Thus, the filing of a § 3731 certification is not
    merely an administrative formality; it serves the
    important purpose of assuring the defendant’s pro-
    tection from undue delay.

(emphasis in original) (internal quo-
tations and citation omitted).
5648             UNITED STATES v. W. R. GRACE
   Significantly, the United States Attorney’s decision to
appeal requires the concurrence of the Solicitor General of the
United States. See 

(concluding
that the Solicitor General’s approval means there is “no sig-
nificant danger that the appeal will be frivolous, warranting
dismissal rather than disposition on the merits”); 

(“[T]he Solicitor General authorized the
appeal. This authorization likely ensures that the purposes of
section 3731 were met.”); see also 

(referring to the United States Attorney obtaining approval
from the Solicitor General “in accordance with internal
Department of Justice policy”); United States v. Colomb, 

, 296-97 (5th Cir. 2005) (noting that the appeal fol-
lowed the government obtaining approval of the Acting Solic-
itor General). Thus we expect the concerns about frivolous or
disruptive attempts to involve us prematurely in ongoing trial
proceedings that animated our previous certification-plus rule
(and trouble our concurring colleague) will be addressed by
the government’s wise and careful invocation of § 3731
appeals.

   [3] In sum, we conclude that the United States Attorney’s
certification in this case suffices to establish our jurisdiction
to hear the government’s interlocutory appeal. We therefore
turn to the government’s challenges to the district court’s pre-
trial orders.

         III.   The Pretrial Case Management and
                    Enforcement Orders

   The government advances several arguments why the chal-
lenged pretrial orders are flawed: First, the district court
lacked the authority to require in its March 2005 order that the
government provide a pretrial witness list; second, even if the
court had such authority, it could not require a final list, espe-
cially a year before trial; finally, the exclusionary effect of the
enforcement orders was an inappropriate sanction. In
response, the defendants argue that the district court had
                 UNITED STATES v. W. R. GRACE                5649
authority to order witness lists and acted within its discretion
in enforcing its orders. We agree with the defendants.

A.   Authority

   We begin with the principle that the district court is
charged with effectuating the speedy and orderly administra-
tion of justice. There is universal acceptance in the federal
courts that, in carrying out this mandate, a district court has
the authority to enter pretrial case management and discovery
orders designed to ensure that the relevant issues to be tried
are identified, that the parties have an opportunity to engage
in appropriate discovery and that the parties are adequately
and timely prepared so that the trial can proceed efficiently
and intelligibly.

   The principal orders at issue are the district court’s March
2005 order that, among other things, required the government
to disclose by September 30, 2005 a “finalized list of witness-
es”; and the court’s enforcement orders that limited the gov-
ernment’s use of witnesses in its case-in-chief (but not
rebuttal) to those who had been timely disclosed. The govern-
ment did not object to the March 2005 order at the time, but
when it filed its proposed witness list in September it pur-
ported to reserve “its right to update its witness list and
exhibit list through the close of all evidence at trial.” The gov-
ernment now argues that the district court had no authority to
require the government to produce such a witness list, particu-
larly not a finalized list one year before trial, and to preclude
the government from calling additional witnesses not dis-
closed by the time of the court’s mandated deadline.

  We disagree. The district court’s March 2005 pretrial order
and the enforcement orders fit comfortably within the court’s
authority under Federal Rules of Criminal Procedure 2 and
16, and its more general inherent authority to manage its
docket. Although our decision in United States v. Hicks, 

(9th Cir. 1996), would suggest otherwise, we disap-
5650               UNITED STATES v. W. R. GRACE
prove of Hicks’ reasoning and overrule it to the extent that it
conflicts with our decision today. Rather, we align ourselves
with the other circuit courts that, although not all relying on
a uniform source of authority, widely agree that a witness dis-
closure order directed to the government is within the district
court’s discretion to impose and enforce.7

   [4] There is a “well established” principle that “[d]istrict
courts have inherent power to control their dockets.” Atchi-
son, Topeka & Santa Fe Ry. Co. v. Hercules Inc., 

, 1074 (9th Cir. 1998) (alteration in original) (internal
quotation marks omitted). Further, “judges exercise substan-
tial discretion over what happens inside the courtroom.”
United States v. Simpson, 

, 1091 (9th Cir.
1991). We have accepted that “ ‘[a]ll federal courts are vested
with inherent powers enabling them to manage their cases and
courtrooms effectively and to ensure obedience to their
orders.’ ” Aloe Vera of Am., Inc. v. United States, 

, 964-65 (9th Cir. 2004) (per curiam) (quoting F.J. Han-
shaw Enters., Inc. v. Emerald River Dev., Inc., 

,
1136 (9th Cir. 2001)).

    Other circuits that have addressed a district court’s author-
ity to require the government to disclose its witness list in
advance of trial have agreed that the court may do so. See
United States v. Cannone, 

, 299 (2d Cir. 1975)
(“The general discretion of district courts to compel the gov-
ernment to identify its witnesses is acknowledged widely
. . . .”). Some have invoked the court’s “inherent power, exer-
cisable under appropriate circumstances, to assure the proper
and orderly administration of criminal justice.” United States
v. Jackson, 

, 1007 (7th Cir. 1975); see United
States v. Napue, 

, 1318 (7th Cir. 1988) (“[A]
district court has the authority to require the government to
  7
   We do not decide whether or to what extent the defense can be com-
pelled to disclose a list of its witnesses before trial, and do not address
those issues here.
                 UNITED STATES v. W. R. GRACE               5651
provide the defendant with such a list . . . . [as] part of the
court’s inherent power”) (internal quotation marks omitted);
United States v. Higgs, 

, 44 n.6 (3d Cir. 1983)
(“While it is true that the government is not automatically
required to make such disclosure, the district court, within its
discretion, may order such disclosure to ensure the effective
administration of the criminal justice system.”) (citation omit-
ted); 

(“It is recognized that wide
latitude is reposed in the district court to carry out success-
fully its mandate to effectuate, as far as possible, the speedy
and orderly administration of justice.”) (internal quotation
marks omitted). Others have not explained the source of
authority, but simply have stated that it is within a district
court’s discretion to order the government to produce a wit-
ness list under appropriate circumstances. See, e.g., United
States v. DeCoteau, 

, 1010 n.2 (8th Cir. 1999)
(“[A] district court in this circuit may exercise its discretion
to require such disclosure in a proper case.”) (internal quota-
tion marks omitted); United States v. Rosales, 

,
1305 (10th Cir. 1981); United States v. Colson, 

, 1391 (11th Cir. 1981); United States v. Kendricks, 

, 1168 (6th Cir. 1980) (per curiam). Finally, some
have grounded the authority in Rule 16 itself, see, e.g., United
States v. Jordan, 

, 101 (4th Cir. 1972), or in a
combination of Rule 16 and Rule 2, see United States v.
Fletcher, 

, 54 (4th Cir. 1996).

   We first examine the rule-based approach. Rule 16 speci-
fies categories of witnesses and documentary evidence that
are subject to mandatory pretrial disclosure. See Fed. R. Crim.
P. 16(a)(1) & (b)(1) (e.g., requiring the government to dis-
close at the defendant’s request a written summary of expert
testimony the government intends to use during its case-in-
chief). The rule also identifies kinds of information that are
not included in the mandatory disclosure categories. See Fed.
R. Crim. P. 16(a)(2) & (b)(2) (e.g., exempting government
investigative or prosecuting documents). With respect to the
district court’s authority, Rule 16(d)(1) permits the court, “for
5652               UNITED STATES v. W. R. GRACE
good cause, [to] deny, restrict, or defer discovery or inspec-
tion, or grant other appropriate relief,” and Rule 16(d)(2)
grants the court broad authority to enforce “this rule,” includ-
ing by any order “that is just under the circumstances.”

   [5] Congress has thus addressed the kinds of information
the government and defendants are obligated to provide to
each other before trial by way of discovery and the district
court’s authority to enforce those obligations. Rule 2 bolsters
that authority by instructing that the rules “are to be inter-
preted to provide for the just determination of every criminal
proceeding, to secure simplicity in procedure and fairness in
administration, and to eliminate unjustifiable expense and
delay.” The thrust of Rule 16 — viewed in light of Rule 2 —
is to allow the district court to ensure that the parties comply
with the letter and spirit of the rule. Much of the govern-
ment’s challenge to the district court’s orders here can be dis-
posed of under the express provisions of Rule 16 — such as
the disclosure of scientific reports and expert witnesses,
which we shall discuss presently.8

   Although Rule 16 does not expressly mandate the disclo-
sure of nonexpert witnesses, it is not inconsistent with Rule
16 and Rule 2 for a court to order the government to produce
a list of such witnesses as a matter of its discretion. See

(citing Rule 16 and Rule 2 in uphold-
ing an order for disclosure of witnesses); 

(citing Rule 2 in rejecting the government’s argument
that the district court’s authority to order it to disclose its wit-
ness list should be conditioned on the defense’s showing of
materiality and reasonableness). Above all, nothing in Rule 16
expressly prohibits the district court from ordering additional
pretrial discovery or disclosures that will also further the
objectives set forth in Rule 2. See 

(stating that “the present [Rule 16] is no bar to the order”).
The Supreme Court has recognized that federal courts “may,
  8
   See Fed. R. Crim. P. 16(a)(1)(E)(ii), (a)(1)(F) & (a)(1)(G).
                     UNITED STATES v. W. R. GRACE                       5653
within limits, formulate procedural rules not specifically
required by the Constitution or the Congress.” United States
v. Hasting, 

, 505 (1983).9 Of course, “[w]hatever
the scope of this ‘inherent power,’ . . . it does not include the
power to develop rules that circumvent or conflict with the
Federal Rules of Criminal Procedure.” Carlisle v. United
States, 

, 426 (1996); see 

(“[D]istrict courts have inherent power to control their
dockets, but not when its exercise would nullify the proce-
dural choices reserved to parties under the federal rules.”).
Ordering the pretrial disclosure of nonexpert witnesses does
not “circumvent or conflict” with Rule 16. 

. The rule does not entitle the defendant to a list of such
witnesses, but by the same token it does not suggest that a dis-
trict court is prohibited from ordering such a disclosure. See
  9
   We have previously read Hasting as “limit[ing]” federal courts’ inher-
ent powers to “three specific areas”:
      (1) to implement a remedy for a violation of recognized rights;
      (2) to preserve judicial integrity by ensuring that a criminal con-
      viction rests on appropriate considerations validly before the jury;
      and (3) to deter future illegal conduct.
United States v. Gonsalves, 

, 1320 (9th Cir. 1986); see also
United States v. Simpson, 

, 1090 (9th Cir. 1991). Here, the
government argues that because the district court’s order does not fall
within any of those “three specific areas,” the order is beyond the court’s
inherent powers. Our previous cases read Hasting too narrowly. There is
nothing in that opinion that “limit[s]” the inherent powers to these three
areas. The Supreme Court has, since Hasting, approved several exercises
of inherent power that are beyond the “three specific areas” we thought
Hasting delimited. E.g., Chambers v. NASCO, Inc., 

, 46 (1991)
(district courts have inherent power to punish bad-faith conduct by award-
ing attorneys’ fees to the other side); Thomas v. Arn, 

, 142,
146-47 (1985) (circuit courts have inherent power to establish a rule that
“the failure to file objections to the magistrate’s report waives the right to
appeal the district court’s judgment”). We therefore return to the under-
standing of inherent power that we recognized in United States v. Richter,

, 173-74 (9th Cir. 1973), according to which district courts
have the inherent power to “order the government to divulge names of
prospective witnesses.”
5654                UNITED STATES v. W. R. GRACE

(“[T]he Government fails to distin-
guish between the right of the defendant to demand a list of
witnesses, and the authority of the court to order such disclo-
sure under the appropriate circumstances.”).

   [6] As noted earlier, some courts have found an affirmative
grant of authority to order the pretrial disclosure of all of the
government’s proposed witnesses in Rule 16’s enforcement
provisions (sometimes also invoking Rule 2). In doing so,
these decisions have elided the language of Rule 16(d)(1) and
(2) that appears to focus on enforcing the mandatory disclo-
sure provisions of Rule 16 itself.10 We do not, however, have
to resolve whether Rule 16 alone or in combination with Rule
2 provides sufficient authority for the district court’s orders
regarding nonexpert witnesses. At the very least these rules do
not preclude such orders. Further, they reinforce the logic and
fairness of requiring the government to produce a pretrial wit-
ness list of both experts and nonexperts (subject to appropri-
ate conditions) so that the parties — and the district court —
may be adequately prepared for trial. That is the essential
premise of the court’s inherent power to manage its cases to
ensure the fair and effective administration of the criminal
justice system. See United States v. Richter, 

,
173-74 (9th Cir. 1973) (“It is recognized that wide latitude is
reposed in the district court to carry out successfully its man-
date to effectuate, as far as possible, the speedy and orderly
administration of justice . . . . It would be ill-advised to limit
improvidently this inherent power for fear of misuse.”).11
  10
      By its plain terms, Rule 16 speaks to specified kinds of discovery in
criminal cases, and its enforcement provisions parallel this specificity
rather than addressing the general authority of the court. Rule 16(d)(1)
refers to granting relief related to “discovery or inspection,” which is Rule
16’s title; and (d)(2) authorizes courts to take certain actions “if a party
fails to comply with this rule.” (Emphasis added.) But see, e.g., 

(citing Rule 16 as granting authority to regulate discovery
broadly).
   11
      Richter predated the 1993 amendments to Rule 16, in which Congress
adopted provisions concerning expert witness disclosures. Notwithstand-
                   UNITED STATES v. W. R. GRACE                    5655
   Insofar as we held in Hicks that a district court has no
authority to order the government to produce a pretrial wit-
ness list beyond that specified in Rule 16, we now join our
sister circuits and hold to the contrary. See 

. In retrospect, our decision did not correctly distinguish
between the mandatory disclosure requirements of Rule 16
and the district court’s discretionary authority to order pretrial
disclosures of government witnesses in appropriate circum-
stances. In Hicks, the district court had ordered the parties to
exchange witness lists and short summaries of anticipated wit-
ness testimony. 

The defendant (not the govern-
ment) objected, but eventually complied and appealed the
district court’s order, arguing that “the district court did not
have the authority under Rule 16 . . . to issue such an order.”

stating that a “district court that orders the
Government and the defendant to exchange witness lists and
summaries of anticipated witness testimony in advance of trial
has exceeded its authority under Rule 16 of the Federal Rules
of Criminal Procedure and has committed error.” 

(emphasis added). To support this conclusion, Hicks relied on
Congress’ rejection in 1975 of a proposed amendment to Rule
16 that would have required both the government and the
defense to disclose their witnesses before trial. We inferred
from this rejection that Congress intended to deny a district
court any authority to order any pretrial witness disclosure
other than that expressly provided under Rule 16. See 

the legislative history such a sweeping
denial of authority was not an inevitable conclusion. There
was no suggestion that Congress intended to bar district
courts from exercising their discretionary authority to order
pretrial discovery and disclosures from the government under

ing these amendments, we do not read Congress as precluding district
courts’ authority to regulate the discovery of nonexpert witnesses just
because Congress specifically adopted certain rules pertaining to expert
witness disclosures. The reasons for not limiting such authority are well
expressed in 

.
5656             UNITED STATES v. W. R. GRACE
terms and conditions that courts normally use to manage the
fair and efficient conduct of trials. Rather, Congress was con-
cerned that a mandatory disclosure rule would discourage
government witnesses from testifying and lead to witness
intimidation. See 

(“The conference
committee expressed concern that such a requirement would
discourage witnesses from testifying and would lead to
‘improper contact directed at influencing their testimony.’ ”)
(quoting H.R. Rep. No. 94-414, at 12 (1975) (Conf. Rep.),
reprinted in 1975 U.S.C.C.A.N. 713, 716). Congress said
nothing about the district court’s discretion to order such a
pretrial disclosure, subject to the court’s ability to tailor dis-
closures to specific concerns in a particular case, including the
use of protective orders. See, e.g., United States v. Fort, 

, 1131 (9th Cir. 2007). We therefore conclude that
Hicks adopted an overly broad reading of Rule 16 and unnec-
essarily restricted the district court’s discretionary authority to
order discovery from the prosecution.

   [7] In sum, we hold that a district court, consistent with
Rule 16 and Rule 2 and as part of the court’s inherent author-
ity to manage its docket, may in appropriate circumstances
require the government to disclose a final list of its proposed
trial witnesses and has the authority to enforce such an order.
Hicks is overruled to the extent that it applied to such disclo-
sures by the government.

B.     The District Court’s Exercise of its Authority

   The government contends that, even if the orders were
authorized, both the March 2005 order and the enforcement
orders were an abuse of the court’s discretion. We do not
agree. Although a district court’s discretion to order pretrial
discovery is not unfettered, the district court did not abuse its
discretion here.

  [8] We first address the court’s orders insofar as they con-
cerned expert disclosures and scientific reports, the disclosure
                 UNITED STATES v. W. R. GRACE                 5657
of which is governed by Rule 16(a). Subsections (a)(1)(G),
(a)(1)(E)(ii) and (a)(1)(F) of Rule 16 require the government
to disclose, at the defendant’s request, a summary of any
expert witness testimony the government intends to use dur-
ing its case-in-chief at trial as well as “the bases and reasons
for those opinions”; documents within the government’s pos-
session, custody or control that the government intends to use;
and certain scientific reports. The March 2005 case manage-
ment order expressly implemented those provisions by requir-
ing the timely disclosure of the government’s expert witnesses
and an expert report tailored to the issues on which each
expert is expected to testify. The December 2005 enforcement
order also clarified that expert disclosures must identify the
documents or information that the expert reviewed in prepar-
ing his or her report, a condition well within Rule 16’s
requirement that expert disclosures describe “the bases and
reasons for those opinions.” The district court’s orders impos-
ing and enforcing these expert witness disclosures were
clearly within its Rule 16 authority and not an abuse of its dis-
cretion.

   Next, as to both expert and nonexpert witnesses, the gov-
ernment argues that requiring it to disclose its final list of wit-
nesses a year before trial was unreasonable and that the
district court’s exclusion of witnesses and reports not dis-
closed by December 5, 2005 was an inappropriate sanction.
We reject the government’s objections for several reasons.

   [9] First, the district court’s March 2005 order set a rela-
tively early deadline for the government to provide a final
witness list in advance of the then-scheduled September 2006
trial. The record reflects that the court had good reason to
impose such a deadline, however; the court believed that the
deadline would bring the necessary focus and organization to
ready the case for trial. The charged conspiracy reaches back
nearly 30 years, the government now proposes to call more
than 200 witnesses, there are many defendants and allega-
tions, and millions of pages of documents have been produced
5658               UNITED STATES v. W. R. GRACE
during discovery. Such a complex case poses special chal-
lenges to the parties in preparing for trial and to the court in
managing the litigation. Moreover, the government itself had
initially suggested a September 2005 trial date, indicating to
the district court that the government could be prepared for
trial by then. When asked in the March 2005 status confer-
ence whether the government could make its expert disclo-
sures by the end of September, the prosecutor responded,
“[t]hat would be good,” and when asked about a finalized list
of witnesses and trial exhibits by the end of September, he
said he “d[id]n’t have a problem with that.” The government
also did not object to the disclosure deadlines set by the
March 2005 order. Rather, when it filed its supposed “final”
list in September 2005 it simply and unilaterally reserved its
“right” to supplement the list up to the time of trial. Given the
size and complexity of the case and the government’s acqui-
escence in the dates for final witness and document disclo-
sures, the district court’s March 2005 order was reasonable
and not an abuse of discretion.12

   Second, the government mischaracterizes the enforcement
orders as an exclusionary “sanction.” The enforcement orders
were not imposed as a sanction; they simply enforce the ear-
lier pretrial order requiring the timely identification of trial
witnesses and documentary evidence. In March 2005, when
the government told the court it was prepared to try the case
that September, the government estimated it would be calling
60 to 80 witnesses; by the time it filed its witness list on Sep-
tember 30, the number of witnesses had grown to 233 and
counting. At the December 2005 status hearing, the district
court rejected the government’s arguments for expanding the
list further, finding that the government “cannot now credibly
claim that it is necessary to continue adding witnesses to an
already unwieldy list.” Accordingly, it ruled that “the govern-
  12
    Notably, the district court did not take a rigid approach, effectively
converting the September 30 deadline to a December 5 deadline by virtue
of the December 2005 order.
                UNITED STATES v. W. R. GRACE               5659
ment’s presentation at trial will be limited to those witnesses
that have been disclosed as of the filing of this Order [i.e.,
December 5, 2005],” later clarifying in the February 2006
order that this limitation applied only to the government’s
case-in-chief, not to rebuttal witnesses. Given the many dis-
cussions the court had with counsel about the fluid nature of
the government’s evolving case and the court’s expressed
concerns that the government seemed unable to get its trial
preparation under control, it could hardly have been a surprise
that the court froze the witness list when and as it did.

   Third, even if we were to view the enforcement orders as
a sanction, they still would not be an abuse of the court’s dis-
cretion. At the outset, we emphasize that we are addressing
only the preclusive effect of the enforcement orders as they
currently stand because, apart from this interlocutory appeal,
the government has thus far sought no relief from the district
court’s orders with respect to any particular excluded witness.
We do not know whether the district court would be per-
suaded to allow the government to add or substitute one or
more new witnesses for good cause. See, e.g., D. Mont. R. 7.3
(permitting a party to seek relief from the district court if it
finds new evidence and can demonstrate good cause). None-
theless, the government relies on United States v. Finley, 

(9th Cir. 2002), for the proposition that the exclu-
sion of witnesses can be imposed as a sanction only when the
district court finds the violation of a disclosure order was
“willful and motivated by a desire to obtain a tactical advan-
tage.” 

(quoting Taylor v. Illinois, 

,
415 (1988)). Because the district court made no such findings
in this case, the government contends the exclusion orders
cannot stand. Finley, however, like Taylor, involved a defen-
dant’s right to present evidence, not the government’s, and
has no bearing here. See 

(“Because
the Supreme Court has recognized that ‘[f]ew rights are more
fundamental than that of an accused to present witnesses in
his own defense,’ 

, courts should use
5660                UNITED STATES v. W. R. GRACE
particular caution in applying the drastic remedy of excluding
a witness altogether.”).

   Finally, the government argues that even if a court can
legitimately compel the government to disclose its witness
list, it cannot force the government to finalize that list on pen-
alty of exclusion of later discovered witnesses, particularly a
year before trial. Relying on United States v. Gatto, 

, 1046 (9th Cir. 1985), it contends the district court’s
orders violated the separation of powers principle by improp-
erly commandeering the government’s investigatory and pro-
secutorial functions. Of course, the orders did no such thing
— as we have discussed, they dealt with managing the pro-
ceedings inside the courtroom, not with the government’s per-
formance of its prosecutorial duties outside the courtroom.
The government’s discretion to investigate and present its
case does not override the district court’s authority to manage
the trial proceedings — including by setting discovery and
disclosure deadlines — and Gatto does not hold otherwise.13

   The government’s reliance on Gatto is misplaced. That
case involved a district court order requiring the government
to provide discovery in accordance with Rule 16. Four weeks
before trial and well after the discovery disclosure deadline
had passed, the government belatedly learned that cooperating
state officials had relevant documents that should have been
produced to the defendants. Invoking its authority under both
Rule 16(d)(2) and the court’s inherent supervisory power, the
district court precluded use of the evidence during the govern-
  13
    Although Gatto has been bemoaned as “lay[ing] down an inflexible
rule — the government has an absolute right to call its lately acquired wit-
ness whatever the consequences to the administration of justice in other
respects,” United States v. Schwartz, 

, 660 (9th Cir. 1988)
(Hupp, J., concurring), we disavow that it did create such an “absolute
rule,” as we explain in text. As the majority in Schwartz itself recognized,
a district court may exclude documents or witnesses for failure to comply
with the court’s pretrial or discovery orders. See 

.
                 UNITED STATES v. W. R. GRACE                 5661
ment’s case in-chief. 

On the government’s § 3731
appeal, we held that the court lacked authority under either its
supervisory power or Rule 16. As to the former, we empha-
sized that the government’s delay in disclosure had not vio-
lated “any constitutional provision, federal statute, specific
discovery order, or any other recognized right except perhaps
[R]ule 16.” 

There was no need to resort to the
court’s inherent supervisory power to create any other remedy
for a violation of Rule 16 because the rule itself contains spe-
cific remedies for its violation. See 

Rule 16, we
expressly held that the government’s failure to disclose the
documents earlier did not violate the rule because the state-
held documents were not in the government’s actual posses-
sion. 

   Unlike Gatto, here the government would violate Rule 16
if it were to call expert witnesses who were not timely dis-
closed. Therefore, the district court may properly rely on its
Rule 16 authority where appropriate to enforce its orders. As
to the disclosures not mandated by Rule 16, the court has
inherent authority to enforce its specific discovery order,
which the government would violate if it were to call undis-
closed nonexpert witnesses. First, with respect to the expert
disclosures, the district court’s March 2005 order was well
within the bounds of Rule 16, as we have already discussed.
The government did not object to the order, but instead
reserved to itself a right to supplement its disclosures through
the close of evidence at trial. The district court had the author-
ity under Rule 16(d)(2) to reject this unilateral reservation of
rights and enforce the discovery requirements mandated by
the rule; it did not need to resort to its inherent authority. Sec-
ond, as to the March 2005 order’s mandate to disclose nonex-
pert witnesses, who do not come within the express terms of
Rule 16, nothing in Gatto — or in Rule 16 itself, as we have
discussed in Section III(A) — precludes a district court from
relying on its inherent authority to order such witness disclo-
sures or to enforce its order. As Gatto expressly noted, the
government had not violated “any . . . specific discovery
5662             UNITED STATES v. W. R. GRACE
order.” 

Here there was such an order, and if it is
violated, the district court may exclude evidence as a sanc-
tion. Although there are limits to the district court’s inherent
authority, the district court here is well within its authority to
manage its docket in enforcing a valid pretrial discovery
order. See United States v. Talbot, 

, 187-88 & n.5
(9th Cir. 1995)(distinguishing Gatto and upholding exclusion
of government witnesses for violation of pretrial disclosure
order).

                       IV.   Conclusion

   In conclusion, we hold that the United States Attorney’s
§ 3731 certification to the district court sufficed to invoke our
appellate jurisdiction over this interlocutory appeal. We fur-
ther hold that the district court had authority to order and
enforce the pretrial disclosures of government witnesses and
evidentiary documents and that the district court did not abuse
its discretion in doing so here. Should the government seek
leave to add a specific witness or report it believes is fore-
closed by the district court’s pretrial orders, we leave it to the
district court to address the request in accordance with the
principles we have set forth in this opinion.

  AFFIRMED.



HAWKINS, Circuit Judge, with whom PREGERSON and
WARDLAW, Circuit Judges, join, concurring as to Part III,
and concurring in the judgment:

   We face two closely related issues, both dealing with the
ability of district judges to manage complex criminal trials.
One is whether a district judge may order the government to
provide a final witness list prior to the beginning of trial. This
one the Opinion gets absolutely right, holding that the inter-
ests of trial continuity outweigh any interest in withholding
                   UNITED STATES v. W. R. GRACE                 5663
those names and disclosing them only when the prosecution
deems it appropriate. The other is whether the prosecution can
delay a trial and require an interlocutory appeal on an eviden-
tiary ruling on nothing more than its say so. By my lights, the
Opinion not only gets this one wrong, but also creates along
the way what our colleague Judge Goodwin describes as a
“hazard to navigation” to the efficient and evenhanded admin-
istration of justice in our trial courts.

   For the following reasons, I respectfully part from the por-
tion of the Opinion dealing with 18 U.S.C. § 3731.

  I.    Statutory Text

  According to the majority, the plain language of § 3731
precludes this court from exercising any independent judg-
ment over its own jurisdiction. I disagree.

  The second paragraph of § 3731 provides:

       An appeal by the United States shall lie to a court of
       appeals from a decision or order of a district court
       suppressing or excluding evidence or requiring the
       return of seized property in a criminal proceeding,
       not made after the defendant has been put in jeop-
       ardy and before the verdict or finding on an indict-
       ment or information, if the United States attorney
       certifies to the district court that the appeal is not
       taken for purpose of delay and that the evidence is
       a substantial proof of a fact material in the proceed-
       ing.

   Reading this, the majority believes that it is evident from
the statute’s phrasing that the courts of appeals are forbidden
from applying even the most modest scrutiny to the United
States Attorney’s certification. On my reading, the statute is
ambiguous and nothing in the text compels the majority’s
interpretation.
5664            UNITED STATES v. W. R. GRACE
   We begin with a straightforward proposition: Congress not
only knows how to tell courts of appeals to defer completely
to the United States Attorney, it has done just that in the con-
fines of a remarkably similar certification statute. Under the
Westfall Act, 28 U.S.C. § 2679, when a federal employee is
sued for a wrongful or negligent act, the United States is to
be substituted as the party defendant “[u]pon certification by
the Attorney General that the defendant employee was acting
within the scope of his office or employment at the time of the
incident out of which the claim arose.” 

A
separate subsection of the same Act provides that a suit com-
menced in state court shall be removed to federal court upon
the Attorney General’s scope-of-employment certification,
and that “[t]his certification of the Attorney General shall
conclusively establish scope of office or employment for pur-
poses of removal.” 

(emphasis added). Impor-
tantly, there is no similar provision in § 2679(d)(1); Congress
never stated that the Attorney General’s certification would be
conclusive for the substitution inquiry.

   The Supreme Court has considered both the removal and
substitution subsections of the Westfall Act. Interpreting the
removal provision, the Court explained that “Congress gave
district courts no authority to return cases to state courts on
the ground that the Attorney General’s certification was
unwarranted. . . . For purposes of establishing a forum to
adjudicate the case . . . § 2679(d)(2) renders the Attorney
General’s certification dispositive.” Osborn v. Haley, 

, 894 (2007). This reading makes perfect textual
sense, for if it were “open to a district court to remand a
removed action on the ground that the Attorney General’s cer-
tification was erroneous, the final instruction in § 2679(d)(2)
would be weightless. The Attorney General’s certification
would not ‘conclusively establish scope of office or employ-
ment’ for either trial or removal.” 

  By contrast, the Supreme Court has held that the scope-of-
employment certification under § 2679(d)(1)—the substitu-
                    UNITED STATES v. W. R. GRACE                        5665
tion provision—is reviewable. Gutierrez de Martinez v.
Lamagno, 

, 434 (1995). As a matter of syntax,
§ 2679(d)(1) cannot be meaningfully distinguished from
§ 3731. That section of the Westfall Act provides, in full:

      Upon certification by the Attorney General that the
      defendant employee was acting within the scope of
      his office or employment at the time of the incident
      out of which the claim arose, any civil action or pro-
      ceeding commenced upon such claim in a United
      States district court shall be deemed an action
      against the United States under the provisions of this
      title and all references thereto, and the United States
      shall be substituted as the party defendant.

28 U.S.C. § 2679(d)(1) (emphasis added).

   In Gutierrez de Martinez, the Supreme Court framed “[t]he
sole question . . . [as] who decides on which side of the
[scope-of-employment] line the case falls: the local United
States Attorney, unreviewably or, when that official’s deci-
sion is contested, the 

. Unlike the
majority in the present case, the Court did not hold that the
phrase “[u]pon certification by the Attorney General,” or the
word “shall,”2 made evident Congress’s intent to preclude
  1
      The local United States Attorney was acting on behalf of the Attorney

.
    2
      The majority emphasizes the word “shall” in § 3731, suggesting, I take
it, that we must exercise jurisdiction if the United States Attorney certifies
the necessary facts. As a textual matter, the word provides very little guid-
ance, even aside from the reality that “legal writers sometimes use, or mis-
use, ‘shall’ to mean ‘should,’ ‘will,’ or even ‘may.’ ” Gutierrez de

n.9; see also 

n.9 (noting that Federal
Rule of Civil Procedure 16(e) and Federal Rule of Criminal Procedure
11(b) “use the word ‘shall’ to authorize, but not to require, judicial
action”). I agree that we have no discretion to decline jurisdiction if the
United States Attorney’s certification obligation is satisfied. I dispute only
the nature of that obligation, which is a question upon which the word
“shall” has no bearing.
5666               UNITED STATES v. W. R. GRACE
courts from looking beyond the Attorney General’s naked cer-
tification. Instead, the Court believed that “Congress did not
address this precise issue unambiguously, if at all . . . . [T]he
Westfall Act is, on the ‘who decides’ question we confront,
open to divergent interpretation.”3 

   Where the Supreme Court perceived “statutory fog,” 

the majority finds congressional intent that “has been
expressed in reasonably plain terms.” We are told that
“[n]othing in the statute requires the government to go further
and prove that the evidence suppressed or excluded by the
district court is actually material to the proceeding before our
jurisdiction can attach.” A fair point, but not one that estab-
lishes the statute is unambiguous. Using the same reasoning,
it seems clear that nothing in the statute prohibits the court
from examining the United States Attorney’s certification.

   The majority finds guidance in the portion of § 3731 that
reads, “The provisions of [§ 3731] shall be liberally construed
to effectuate its purposes.” Congress did not explicitly state its
purposes, so this provision invites some question-begging.4
  3
     I rely on Gutierrez de Martinez only for my textual analysis. Although
the case resulted in the outcome I argue for here, the contrast between the
Westfall Act and § 3731 precludes me from suggesting that the Supreme
Court resolved our ultimate inquiry. For example, in Gutierrez de Marti-
nez, the Attorney General’s certification would have led to an automatic
dismissal of the case on sovereign immunity grounds, and “when a Gov-
ernment official’s determination of a fact or circumstance—for example,
‘scope of employment’—is dispositive of a court controversy, federal
courts generally do not hold the determination unreviewable.” Gutierrez
de 

. And, as discussed, the inclusion of the word
“conclusively” with respect to removal, and its absence with respect to the
substitution issue, provided strong textual evidence that the latter was
reviewable. See 

see also Osborn v. Haley, 

, 895
(2007). Additionally, the court looked to the particular and unique impetus
that led to adoption of the Westfall 

. That legisla-
tive backdrop does not apply here.
   4
     The majority wisely ignores the government’s invocation of United
States v. Wilson, which held that § 3731 was “intended to remove all statu-
                    UNITED STATES v. W. R. GRACE                       5667
The majority posits that “[t]he purpose of § 3731 is to give the
government a window of opportunity to challenge a district
court’s exclusion of allegedly material evidence before jeop-
ardy attaches; we should not, therefore, read into the statute
an unwritten additional hurdle, even if well intentioned.”

   This reading distorts Congress’s intent. The majority’s
description would be accurate if there were no certification
requirement in the statute. But that requirement exists, and it
undoubtedly reflects Congress’s concern that the government
might abuse its appellate rights. Indeed, the majority recog-
nizes that “[b]y specifying that the United States Attorney
must certify the appeal, Congress plainly intended that the
decision to take an interlocutory appeal be a serious, consid-
ered judgment, not simply an administrative formality.”

   Deterring frivolous appeals is as much of a statutory pur-
pose as enabling worthy ones, and the Loud Hawk rule liber-
ally construes the certification requirement to effectuate both
purposes. Far from being unwritten hurdles, the jurisdictional
conditions identified by Loud Hawk are drawn straight from
§ 3731’s text. The majority, however, appears content to lib-
erally construe the first half of the paragraph, while strictly
construing the second half.

   Interestingly, of the three jurisdiction-conferring provisions
of § 3731, only the one at issue in this case requires the gov-
ernment to certify facts to the district court.5 This suggests

tory barriers to Government appeals and to allow appeals whenever the
Constitution would permit.” 

, 337 (1975). The government
fails to appreciate that Wilson dealt with an entirely separate and indepen-
dent portion of § 3731 that enables the prosecution to appeal, in a criminal
case, “a decision, judgment, or order of a district court dismissing an
indictment or information or granting a new trial after verdict or judg-
ment.” The Wilson Court’s conclusion that Congress intended to “allow
appeals whenever the Constitution would permit” rested on legislative his-
tory that applied exclusively to this paragraph of § 3731. See 

   5
     The provision that concerns us in this case is found in the second para-
graph of § 3731. The first and third paragraphs of this section read in full:
5668                UNITED STATES v. W. R. GRACE
Congress was especially concerned that federal prosecutors
might abuse the ability to interlocutorily appeal suppression
orders,6 thereby unnecessarily disrupting proceedings, and
that certification was supposed to act as a meaningful check.
While it is possible that Congress decided to counter potential
prosecutorial abuse by requiring an unreviewable, boilerplate
certification by the prosecution alone, the text of § 3731 does
not unambiguously express this intent.

  II.    Legislative History

   Where the statutory language is ambiguous, we “turn to the
legislative history for evidence of congressional intent.” Dent
v. Cox Commc’ns Las Vegas, Inc., 

, 1145 (9th
Cir. 2007). Although the legislative history fails to directly
resolve the question presented here, it does shed some light on
Congress’s purpose in adopting § 3731’s second paragraph.

   The second paragraph was adopted, with slightly different

    In a criminal case an appeal by the United States shall lie to a
    court of appeals from a decision, judgment, or order of a district
    court dismissing an indictment or information or granting a new
    trial after verdict or judgment, as to any one or more counts, or
    any part thereof, except that no appeal shall lie where the double
    jeopardy clause of the United States Constitution prohibits further
    prosecution.
    ....
      An appeal by the United States shall lie to a court of appeals from
      a decision or order, entered by a district court of the United
      States, granting the release of a person charged with or convicted
      of an offense, or denying a motion for revocation of, or modifica-
      tion of the conditions of, a decision or order granting release.
   6
     For stylistic purposes, I will rely on “suppression orders,” “suppressing
evidence,” and like phrases as shorthand for an “order of a district court
suppressing or excluding evidence or requiring the return of seized prop-
erty in a criminal proceeding.”
                    UNITED STATES v. W. R. GRACE                      5669
language,7 as part of the Omnibus Crime Control and Safe
Streets Act of 1968, Pub. L. No. 90-351, tit. VIII, § 1301(a),
82 Stat. 197, 237-38. The original Senate and House bills did
not contain the provision; it was proposed as an amendment
to the Senate bill by Senator Allott of Colorado. United States
v. Greely, 

, 1104 n.2 (D.C. Cir. 1969) (per
curiam); 114 Cong. Rec. 14787, 14787-89 (1968). The
amendment was identical to a previously-passed House bill,
H.R. 8654, 90th Cong. (1967). Senator Allott’s remarks and
the report accompanying H.R. 8654 reveal three concerns
addressed by the provision.

   First, the legislation was designed to facilitate successful
prosecutions by granting the government an opportunity to
challenge the suppression of important evidence. Senator
Allott hoped that “our law-enforcement agencies will be given
the tools with which to launch a meaningful attack on the crit-
ical problem of crime in this country,” and he explained that
“[i]t is obviously much better to prove a case with tangible
and concrete evidence than upon oral testimony and observa-
  7
    The original language of the certification requirement provided that the
United States Attorney was to certify “ ‘to the judge who granted such
motion that the appeal is not taken for purpose of delay and that the evi-
dence is a substantial proof of the charge pending against the defendant.’ ”
See United States v. Greely, 

, 1104 (D.C. Cir. 1969) (per
curiam). The requirement was amended to its current form in 1971 as part
of the Omnibus Crime Control Act of 1970, Pub. L. No. 91-644, tit. III,
84 Stat. 1880, 1890 (1971). Although the 1971 amendment slightly altered
the language of the certification requirement, the primary purpose of
amending the suppression order paragraph was to make “the Govern-
ment’s right to appeal an order suppressing evidence applicable to all
criminal proceedings, including probation revocation hearings, not merely
to pretrial suppressions.” S. Rep. No. 91-1296, at 2 (1970); see also
United States v. Hines, 

, 174-5 (10th Cir. 1969) (holding that
the government’s right to appeal under the 1968 statute did not apply to
probation revocation hearings). One final amendment to the now-second
paragraph corrected a grammatical error. Violent Crime Control and Law
Enforcement Act of 1994, Pub. L. No. 103-322, tit. XXXIII, § 330008(4),
108 Stat. 1796, 2142.
5670             UNITED STATES v. W. R. GRACE
tion of witnesses.” 114 Cong. Rec. at 14788 (statement of
Sen. Allott). The House report noted that an order granting a
motion to suppress evidence is often “in effect, a final order
bringing the prosecution to an end, for the Government is
unable to proceed without the suppressed evidence.” H.R.
Rep. No. 90-603, at 2 (1967).

   Second, the provision was intended to lead to “the develop-
ment of a complete body of law regarding the legality of
searches and seizures presently hampered by the inability of
the Government to bring to the appellate courts significant
cases” arising out of suppression orders. 

“[T]he law
of search and seizure and confessions [was] highly uncertain,”
and the amendment would ameliorate that uncertainty. 114
Cong. Rec. at 14788 (statement of Sen. Allott) (internal quo-
tation marks omitted). In United States v. Dior, we recognized
this concern, noting that the “the overriding purpose of the
provision permitting immediate government appeals from
suppression orders was to deal with the harm which the lack
of government appeals worked on the development of the law
of suppression.” 

, 356 (9th Cir. 1982).

   These two goals were not to come at the expense of a crim-
inal defendant’s rights. A report authored by the President’s
Commission on Law Enforcement and Administration of Jus-
tice, cited favorably by Senator Allott, stated that “[w]here the
prosecution is permitted to appeal from pretrial orders, rules
should be established to protect the defendant’s interest in
obtaining a speedy trial.” 114 Cong. Rec. at 14789. The Com-
mission admonished the government that “appeals should not
be taken routinely from every adverse pretrial ruling. They
should be reserved for cases in which there is a substantial
law enforcement interest.” 

Committee on the
Judiciary stressed that the “rights of the defendants, of course,
have been taken into consideration and are in no way
impinged upon” by the bill. H.R. Rep. No. 90-603, at 3. The
provision required the prosecution to pursue appeals within
thirty days of the district court’s decision and to prosecute
                   UNITED STATES v. W. R. GRACE                      5671
them “diligently.”8 The courts of appeals were expected to
dispose of these appeals “with despatch so that the interest of
justice, both on the part of the defendant and the Government,
will be met as quickly as possible.” 

nothing in the legislative history that speaks
directly to the propriety of courts reviewing the United States
Attorney’s certification. By revealing Congress’s concerns,
however, the history guides us in our efforts to liberally con-
strue the statute in order to effectuate all of its purposes.

  III.    Proper Interpretation of § 3731

   The legislative history confirms that Congress was not con-
cerned exclusively with facilitating successful prosecutions;
rather, Congress was also eager to see the courts develop a
coherent body of search and seizure law, and was solicitous
of defendants’ rights. It is these latter goals that inform our
understanding of the certification requirement.

   There is no dispute that the government is forbidden from
appealing for the purpose of delay or from an order suppress-
ing evidence that is insubstantial or immaterial, and Loud
Hawk does not modify those substantive conditions. The pre-
cise question before us concerns the procedure by which Con-
gress chose to enforce these restrictions: How, in other words,
does the certification requirement impact our ability to ensure
that the government is complying with the jurisdictional con-
ditions?

  If the same conditions were present without a certification
requirement, we would presumably have the authority and
duty to ensure that they were satisfied. See Arbaugh v. Y&H
Corp., 

, 514 (2006) (stating that courts “have an
  8
   The fourth paragraph of § 3731 provides: “The appeal in all such cases
shall be taken within thirty days after the decision, judgment or order has
been rendered and shall be diligently prosecuted.”
5672             UNITED STATES v. W. R. GRACE
independent obligation to determine whether subject-matter
jurisdiction exists, even in the absence of a challenge from
any party”). If, for example, the government violated the
fourth paragraph of § 3731 by filing its notice of appeal more
than thirty days after the pertinent order, this court would con-
sider dismissing the appeal, even though the statute does not
expressly grant us the right to independently review the time-
liness of the filing. See, e.g., United States v. Belgarde, 

, 1180 (9th Cir. 2002) (considering timeliness of
§ 3731 filing); United States v. Shaffer, 

, 686 n.3
(9th Cir. 1986) (same).

   Given this presumptive ability to determine our own juris-
diction, the majority must have concluded that the second
paragraph of § 3731 not only expressly imposes an obligation
on the United States Attorney, but also silently strips this
court of its authority to review jurisdictional facts. We are not,
however, told why Congress would wish to take the highly
unusual step of precluding us from independently reviewing
our jurisdiction.

   Section 3731 serves a gatekeeping function by balancing
the prosecution’s desire to appeal suppression orders with the
defense’s and court’s interest in a prompt and orderly trial.
Congress may have tasked prosecutors with reviewing poten-
tial interlocutory appeals in the first instance, but experience
with certification provisions in two other significant contexts
suggests that Congress did not intend to wholly outsource our
jurisdictional inquiry.

   In civil actions, courts of appeals may entertain an interloc-
utory appeal from a non-final district court order if the district
judge certifies that he is “of the opinion that such order
involves a controlling question of law as to which there is
substantial ground for difference of opinion and that an imme-
diate appeal from the order may materially advance the ulti-
mate termination of the litigation.” 28 U.S.C. § 1292(b). The
certification “serves the dual purpose of ensuring that [appel-
                 UNITED STATES v. W. R. GRACE               5673
late] review will be confined to appropriate cases and avoid-
ing time-consuming jurisdictional determinations in the court
of appeals.” Coopers & Lybrand v. Livesay, 

,
474-75 (1978). Importantly, though, once the district judge
opens the gate to this court, we exercise complete, undeferen-
tial review to determine whether the court properly found that
§ 1292(b)’s certification requirements were satisfied. James v.
Price Stern Sloan, Inc., 

, 1068 n.6 (9th Cir.
2002); In re Cement Antitrust Litig., 

, 1026 (9th
Cir. 1982). Only the district judge’s decision to deny certifica-
tion escapes our scrutiny. Executive Software N. Am., Inc. v.
U.S. Dist. Court, 

, 1550 (9th Cir. 1994); Oppen-
heimer v. L.A. County Flood Control Dist., 

(9th
Cir. 1972) (per curiam).

   Our review of a district court’s decision to grant or deny a
habeas corpus petitioner’s request for a Certificate of
Appealability (“COA”) is even broader. “In federal habeas
corpus proceedings, . . . the exercise of appellate jurisdiction
is dependent entirely upon the issuance of a COA.” Phelps v.
Alameda, 

, 726 (9th Cir. 2004); see also 28
U.S.C. § 2253(c). When a district judge or motions panel
grants one, a court of appeals merits panel is not irrevocably
vested with jurisdiction over the appeal. In Phelps v. Ala-
meda, we held that “COAs are not beyond merits panel scruti-
ny”; after one is granted, we retain the “power to vacate or to
contract 

, 728. In fashioning this rule, the
Phelps court acknowledged that “we must be ever mindful of
the gatekeeping and efficiency functions of the certificate of
appealability.” 

(internal quotation marks omitted).
Nevertheless, the court explained, “the pursuit of efficiency
alone does not support an absolute bar against examining the
validity of a COA.” 

contrast to § 1292(b) certifica-
tion denials, when a district court denies a COA, we review
its determination upon the petitioner’s request. See, e.g.,
Stokes v. Schriro, 

, 401 (9th Cir. 2006).

  These two examples show the remarkable nature of the
majority’s ruling. In two core areas of our jurisdiction, Con-
5674             UNITED STATES v. W. R. GRACE
gress has employed the device of certification to assist us in—
without eliminating—our determination of jurisdictional con-
ditions. Without explanation as to why Congress would desire
such a result, the majority tells us that a prosecutor deserves
much greater deference than district judges tasked with analo-
gous gatekeeper-like responsibilities. This simply does not
square with the notion that the decision to exercise jurisdic-
tion, is, at bottom, a judicial, not a prosecutorial, function.

   This paradox is puzzling when one conceives of the § 3731
certification requirement as a gatekeeping device, but it
becomes troubling when the certification is viewed as admon-
itory in nature.

   Certifications are formalities, and in some contexts they
may “perform a cautionary or deterrent function by acting as
a check against inconsiderate action.” Lon L. Fuller, Consid-
eration and Form, 41 Colum. L. Rev. 799, 800 (1941). Parties
in the federal courts are familiar with certification require-
ments that serve a cautionary function. Under Federal Rule of
Civil Procedure 11, attorneys must sign the filings they sub-
mit to the district court, and, upon filing, the attorneys certify
that the papers are not being filed for an improper purpose,
such as to harass or cause delay; that legal contentions are
supported by existing law or by nonfrivolous arguments to
alter existing law; that factual contentions have or are likely
to have evidentiary support; and that denials of factual con-
tentions are warranted on the evidence, belief, or lack of
information. Fed. R. Civ. P. 11(a), (b). At the appellate level,
attorneys’ briefs are subject to specific type-volume limita-
tions, Fed. R. App. P. 28.1(e)(2), 32(a)(7)(B), and they must
contain a Certificate of Compliance that attests that the brief
adheres to the applicable limitations, Fed. R. App. P.
32(a)(7)(C).

   These certifications do not serve a gatekeeper function, and
they are not a means of presenting the courts with useful
information. They serve a much more basic purpose: remind-
                    UNITED STATES v. W. R. GRACE                       5675
ing the parties of their obligation to comply with the courts’
rules. See, e.g., Fed. R. Civ. P. 11 advisory committee’s note
(“The rule continues to require litigants to ‘stop-and-think’
before initially making legal or factual contentions.”). It goes
without saying that we give no weight to such certifications
when determining whether the attorneys have committed any
sanctionable violations; the attorneys’ self-interest makes the
certification inherently untrustworthy.

   The certification requirement in § 3731 serves a purpose
similar to these rules. It provides a forceful reminder to fed-
eral prosecutors that “Congress recognized the importance of
minimizing appellate interference in the trial process,” United
States v. Dior, 

, 356 (9th Cir. 1982), and that the
government is to take seriously its obligation to respect defen-
dants’ rights. By doing so, it implicitly recognizes that United
States Attorneys are biased participants in criminal prosecu-
tions. In the same way that most private attorneys would real-
ize, in the absence of Rule 11’s signing and certification
requirement, that it is improper to pursue legal claims in order
to harass an opponent, few prosecutors needed § 3731 to
inform them that it is improper to file an appeal for the pur-
pose of delay or to disrupt proceedings over an unimportant
piece of evidence. The certification requirements exist in both
instances not simply to describe the regulations, but to put the
parties on notice that Congress and the courts take seriously
the choices attorneys make.

  Given Congress’s clearly expressed concern over the
potential for prosecutors to abuse their appellate rights, it is
hard to believe that the statute requires us to blindly trust
United States Attorneys or those who supervise them.9 The
  9
    While I have great respect for the author of the Opinion and his distin-
guished prior service as a senior Department of Justice official, I wonder
if recent experience might suggest that the comfort he finds in the supervi-
sion of Main Justice officials over the activities of United States Attorneys
might not always be well placed. See John McKay, Train Wreck At the
Justice Department: An Eyewitness Account, 31 Seattle U. L. Rev. 265
(2008).
5676             UNITED STATES v. W. R. GRACE
men and women of the Department of Justice are fine public
servants, dedicated to advancing the public interest. Neverthe-
less, Congress’s recognition of prosecutors’ self-interest is
inherent in § 3731, and we would be unfaithful to congressio-
nal intent if we repudiated that recognition when construing
the statute.

   By my lights, the Loud Hawk rule more effectively
advances the statutory goals than the majority’s approach. For
starters, the Loud Hawk rule is modest. Section 3731 provides
that the government may only appeal the suppression of evi-
dence that “is a substantial proof of a fact material in the pro-
ceeding.” In United States v. Adrian, we held that “we will
find the government to have satisfied this additional jurisdic-
tional requirement if, assuming that the evidence would be
admissible, a reasonable trier of fact could find the evidence
persuasive in establishing the proposition for which the gov-
ernment seeks to admit it.” 

, 491 (9th Cir. 1992)
(emphasis added). Adrian explicitly rejected an interpretation
that would “require the government to demonstrate that the
evidence is highly probative.” 

on the prosecution is thus slight, and this
should allay any fear that Loud Hawk might undermine the
first identifiable purpose of the statute, the facilitation of suc-
cessful prosecutions. Prosecutors pursuing worthy appeals
have little to fear from our precedents. Certifying the § 3731
requirements presents little administrative inconvenience, and
a prosecutor actively involved in the case should have no dif-
ficulty making the necessary showing to the court. In fact, the
majority’s rule and the Loud Hawk rule would lead to diver-
gent results only in those cases in which the government is
appealing for the purpose of delay, or challenging the sup-
pression of immaterial or insubstantial evidence. The
approach the majority adopts today will allow such appeals to
proceed, although this appears to contravene Congress’s clear
intent.
                     UNITED STATES v. W. R. GRACE                         5677
   Congress also hoped that § 3731 would yield a well-
developed body of search-and-seizure jurisprudence. The
Loud Hawk rule furthers this goal in two ways. First, it keeps
the government honest by ensuring that prosecutors do not
take appeals from the suppression of immaterial or insubstan-
tial evidence in order to establish favorable law. As repeat
players in the federal courts, prosecutors have an incentive to
take the long-term view. When an opportunity to make seem-
ingly “good law” comes along, there will be a temptation to
pursue it even if it will have little impact on the case in which
a prosecutor is currently involved. For example, if the district
court suppresses some trivial evidence that the prosecutor
feels is unnecessary in that particular prosecution, she may
appeal anyway if the facts are such that she has the chance to
have the courts of appeals announce a government-friendly
rule of law.10

   Additionally, the Loud Hawk rule favors the development
of the law by enabling the courts of appeals to gain a better
understanding of the facts of appealed cases. Interlocutory
appeals from suppression orders are typically taken before
trial, and the record is therefore necessarily limited. This
means that a panel could be tasked with making new law in
a near factual vacuum. The law develops most properly when
judges can evaluate all facts relevant to a case, and not just
those that pertain to some discrete issue. Under Loud Hawk,
this court gains familiarity with the case by assessing whether
the excluded evidence is a substantial proof of a fact material
in the proceeding. The government will explain why the evi-
dence is meaningful in light of the larger evidentiary picture,
and the defense has the opportunity to contest that explana-
tion. By the time jurisdiction is established, the judges will
  10
     That the government chooses its appeals with care is not mere specu-
lation. Rather, it is the raison d’etre of the policy that requires federal gov-
ernment lawyers to obtain approval from the Office of the United States
Solicitor General before appealing. See FEC v. NRA Political Victory
Fund, 

, 96 (1994).
5678             UNITED STATES v. W. R. GRACE
have a greater sense of what the case is about and the conse-
quences of their potential rulings.

   The Loud Hawk rule also accommodates the statute’s final
purpose, protecting defendants’ rights. The majority finds
comfort in its aspirational rhetoric; my colleagues “expect the
concerns about frivolous or disruptive attempts to involve us
prematurely in ongoing trial proceedings . . . will be
addressed by the government’s wise and careful invocation of
§ 3731 appeals.” Our experience belies this optimism. We
have noted that, “[u]nfortunately, some government attorneys
from time to time treat the § 3731 certification requirement as
a mere formality and even neglect to file the certification in
a timely manner.” United States v. Gantt, 

, 997
(9th Cir. 1999); see 

& n.4 (citing cases from this
and other circuits); cf. United States v. Kojayan, 

,
1324 (9th Cir. 1993) (stating that “[t]he overwhelming major-
ity of prosecutors are decent, ethical, honorable lawyers who
understand the awesome power they wield, and the responsi-
bility that goes with it. But the temptation is always there: It’s
the easiest thing in the world for people trained in the adver-
sarial ethic to think a prosecutor’s job is simply to win”; cit-
ing cases in support).

   If Congress had explicitly made the United States Attor-
neys’ certifications conclusive, as it did for the scope-of-
employment certifications under the Westfall Act when
removal was at issue, I would concede that the court would
be left with no choice but to place our faith in the executive
branch. As it currently reads, however, § 3731 places no such
restrictions on our jurisdictional review. Loud Hawk correctly
demands that we respect our jurisdictional limits, and in doing
so, shield defendants and their speedy trial rights from the
occasional misguided prosecutor.

   Recognizing our concern about improper appeals, the
majority attempts to minimize the impact of its holding. It
insists that we will not blindly trust the government, nor allow
                    UNITED STATES v. W. R. GRACE                      5679
it to disrupt proceedings on a whim. This is because “[i]f the
merits of the appeal independently require us to question
whether the evidence truly is material, the government’s certi-
fication is not conclusive.”

   This non sequitur completely mischaracterizes my position.
I do not assert that the Loud Hawk rule affects our merits
analysis; I recognize that under either the Loud Hawk rule or
the majority’s rule, a § 3731 certification has no bearing on
any substantive assessment of the materiality of suppressed evi-
dence.11 The point remains, however, that the prosecution will
have unchecked authority to pursue interlocutory appeals
from all suppression orders. Even if this court were certain in
a given case that the certification was inaccurate and that the
jurisdictional conditions of § 3731 were violated, we would
be powerless to dismiss, and we would be forced to adjudicate
the appeal on the merits. See e.g., United States v. Laville, 

, 196-98 (3d Cir. 2007) (McKee, J., concurring)
(expressing “concern[ ] that the certification the Government
filed pursuant to 18 U.S.C. § 3731 may be disingenuous,” not-
ing that “it appears to have been reflexively filed,” and “doub-
t[ing] that the § 3731 certification was afforded the
consideration Congress intended,” but acknowledging that
circuit precedent foreclosed the possibility of review). The
majority’s dogged attack on this straw man suggests that it
recognizes this problematic result and that it is uncomfortable
with the breadth of its own ruling.

   By raising our power to expedite review, the majority also
discounts the disruptive value of § 3731 appeals. It currently
takes nine to ten months from the filing of an interlocutory
  11
    The majority somehow finds consolation in the notion that the certifi-
cation will have no bearing on the substantive analysis. The materiality vel
non of the suppressed evidence will not be relevant in many, if not most,
§ 3731 interlocutory appeals. Thus, the Loud Hawk inquiry will typically
be the only opportunity this court has for reviewing the government’s
claim that the evidence suppressed is in fact material.
5680                UNITED STATES v. W. R. GRACE
appeal in a criminal case to its placement on an argument calen-
dar.12 Even if we were able to somehow reduce that time by
half, it would still amount to an inordinate delay in trial pro-
ceedings. Under the naked power the majority gives the gov-
ernment, appeals taken for the purpose of delay will achieve
that purpose regardless of our alacrity.

   Indeed, this very appeal demonstrates the Loud Hawk rule’s
necessity. The government filed its notice of appeal in this
case on March 16, 2006. It filed another interlocutory appeal
regarding a separate issue on August 23, 2006, and yet
another on September 27, 2006. In this appeal, the govern-
ment initially refused to provide the three-judge panel with
any evidence to support its bare certification that the sup-
pressed evidence was material, further delaying proceedings.
The government’s litigation strategy has effectively derailed
the criminal trial, while it no doubt continues its search for
more witnesses and victims. The trial date remains in limbo,
and the defendants’ right to a speedy trial has been completely
frustrated.

   Further, the majority fails to apprehend the design of the
Loud Hawk rule, pointing out that our precedent “does noth-
ing to get the appeal on an argument calendar any faster than
the prevailing certification-only rule,” and that “because we
must first determine the jurisdictional issue and then deter-
mine the merits separately, a final determination under the
Loud Hawk rule may well take longer.” This misses the point.
Even if it were true that the majority’s rule will lead to a
slightly faster disposition of individual § 3731 appeals, that
hardly warrants the conclusion that Loud Hawk is not “effi-
cient.” Loud Hawk provides a deterrent to frivolous appeals.
  12
    As noted above, § 3731 requires the government to file an appeal of
a suppression order within thirty days of the ruling. Although this provi-
sion is salutary, defendants and district courts (which also have an interest
in speedy proceedings) still must endure the substantial lag between the
government’s notice of appeal and our decision.
                    UNITED STATES v. W. R. GRACE                      5681
As with most deterrents, the benefit is not realized in the pro-
cess that follows a breach of the underlying rule, but in the
cases in which the rule is scrupulously observed for fear of
that process.13 To eliminate any confusion, it may be helpful
to review the way in which Loud Hawk operates as a deter-
rent.

   Under the rule we adopt today, the only thing standing
between a prosecutor and an interlocutory appeal is a piece of
paper. A prosecutor faced with an unfavorable suppression
order must decide within thirty days whether to appeal, and
must leave enough time to obtain the approval of the Solicitor
General.14 If the suppressed evidence is of questionable value,
will she take the time to fully consider its materiality? If there
is even the slightest chance that the evidence might bolster the
prosecution’s case or buy time to further prepare its case, the
temptation will be there to forgo any serious consideration of
the certification requirements, secure in the knowledge that
   13
      An example: Traffic regulations are designed to keep drivers and
pedestrians safe, and law enforcement vehicle patrols further that goal by
providing a monitoring and enforcement mechanism. When a violator is
detected and pursued, the momentary danger may be elevated if a high-
speed chase ensues. Are we to conclude that patrols do not keep drivers
and pedestrians safe, then? Do they undermine the very goal they seek to
advance? Hardly. Countless drivers obey the traffic laws because of the
threat of being punished, and that is how the safety gains are achieved in
the aggregate. All other things being equal, so long as the safety gain from
the violations deterred outweighs the elevated levels of danger during
police chases, law enforcement will provide a positive benefit.
   I concede that beyond my own intuition, I “have no evidence that the
certification-plus rule of Loud Hawk is more efficient than simply accept-
ing certification as sufficient to establish our jurisdiction.” I am not the
one seeking to overturn a three-decades-old precedent however. If the
majority seeks to impugn my reasoning because it is not empirically sub-
stantiated, I would think it would offer some evidence of its own.
   14
      Nothing in § 3731 requires the local United States Attorney to seek
the approval of the Solicitor General and nothing in the rule the majority
fashions today gives the courts of appeals the authority to question
whether it has occurred.
5682              UNITED STATES v. W. R. GRACE
we will not question the justification for the decision to
appeal.

   The Loud Hawk rule, by contrast, is conducive to a
thoughtful certification process. Knowing a modest showing
in support of the certification will be required, the prosecutor
has incentive to seriously consider whether to seek an inter-
locutory appeal. Even a hasty decision to challenge the sup-
pression of insubstantial or immaterial evidence might be
reconsidered when actually facing the task of Loud Hawk
compliance. Similarly, a written showing provides the prose-
cutor’s superiors with something they can truly evaluate; they
need not rely on the trial prosecutor’s vague assurances that
the suppressed evidence is important.

   Like the majority, my hope and expectation is that the gov-
ernment will act wisely and carefully when deciding whether
to pursue an interlocutory appeal, and that its unchecked abil-
ity to do so will not diminish the independent judgment of
district judges in the making of important evidentiary rulings.
Unlike the majority, though, I would measure that confidence
with caution. To paraphrase a former President, I would
“trust, but verify.”15 Only this way can we provide the con-
gressionally desired review necessary to safeguard defen-
dants’ rights.

   The Loud Hawk rule secures the continuity of proceedings
by ensuring that the appeal is not taken for purposes of delay
and involves evidence that is both substantial and material.
The rule the majority embraces today permits a prosecutor to
disrupt proceedings with the stroke of a pen. Congress did not
require us to permit that when it enacted § 3731, and we
should not do so now.
  15
    See, e.g., Remarks on Signing the Intermediate-Range Nuclear Forces
Treaty, II Pub. Papers 1455 (Dec. 18, 1987) (Ronald Reagan).