OPINION

COOK, Circuit Judge.

Plaintiff Commercial Law Corporation, P.C. (CLC) sued the Federal Deposit Insurance Corporation (FDIC) in its capacity as receiver for the Detroit-based Home Federal Savings Bank ("the bank"), claiming $176,750 in unpaid attorneys' fees for legal services rendered to the bank in 2008 and 2009. The district court granted the FDIC's motion for summary judgment, concluding that 12 U.S.C. §§ 1821(d)(9)(A) and 1823(e)(1) precluded enforcement of plaintiff's unrecorded fee agreement with the bank. These statutes, which impose documentation requirements for bank agreements, derive from the common-law D'Oench doctrine, an estoppel rule akin to a statute of frauds that shields the FDIC from claims and defenses based on unwritten agreements that reduce bank assets. See D'Oench, Duhme & Co. v. FDIC, 315 U.S. 447, 456-62, 62 S.Ct. 676, 86 L.Ed. 956 (1942); First State Bank of Wayne Cnty. v. City & Cnty. Bank of Knox Cnty., 872 F.2d 707, 715-16 (6th Cir.1989).

CLC appeals, arguing that D'Oench and its statutory progeny do not apply to its legal services arrangement with the bank. We agree and REVERSE.

I.

CLC's principal, L. Fallasha Erwin, served as general counsel for the bank from the late 1980s until the fall of 2009. According to CLC, it began deferring invoicing for services to the bank in 2008 when the bank fell on hard times. The bank continued to struggle, and the Office of Thrift Supervision closed the bank and put it into receivership during the first week of November 2009. CLC claims that, five days before the FDIC takeover, the bank granted it security interests in two bank properties. Inexplicably, CLC waited until late January 2010 to record the attorney liens for these security interests.

Following the bank's failure, CLC filed a claim with the FDIC seeking $176,750 in deferred legal fees for the period May 2008 to November 2009. The FDIC denied the claim, prompting this litigation. Though CLC's complaint mentions the security interest in passing and requests only the "attorneys fees as invoiced plus attorney fees and costs ... wrongfully incurred in this matter," the district court construed the complaint as presenting separate breach-of-contract and attorney-lien claims.

CLC's characterization of its fee arrangement with the bank evolved over the course of this litigation. Although CLC initially denied possessing the original retainer agreement, resting its claim on a series of oral agreements and modifications, CLC's position changed in 2013 after the FDIC moved for summary judgment. Presented with the FDIC's challenge to the enforceability of his undocumented fee arrangement, Erwin produced a 1989 retainer agreement and stated that the deferral of fee payments "was not an amendment of the original retainer agreement." The FDIC moved to strike the newly produced evidence under Federal Rule of Civil Procedure 37(c).

The district court granted the FDIC's motions to strike and for summary judgment. With regard to the newfound retainer agreement, the court found the evidence prejudicial and the delay not "substantially justified," stating that CLC "offered no credible reason why it produced the purported written agreement after the close of discovery." Yet, considering the stricken retainer agreement for purposes of argument, the court deemed the fees arrangement unenforceable against the FDIC because it did not comply with § 1823(e)'s documentation requirements. And, to the extent CLC relied on the security interests to establish the fees claim, the court found them similarly deficient.

Essential to these holdings, the district court rejected CLC's argument that the documentation requirements of § 1823(e) and the D'Oench doctrine apply only to secret agreements affecting traditional banking transactions, like loans. Citing this court's decision in First State Bank of Wayne County v. City & County Bank of Knox County, 872 F.2d at 716, the district court reasoned that § 1823(e) governs agreements implicating both bank assets and liabilities, including liabilities on service contracts.

In addition to these findings, the court found the attorney liens unenforceable under 12 U.S.C. § 1821(e)(12) because they "were taken in contemplation of the Bank's insolvency." The court also acknowledged evidence indicating that Erwin and the bank chairman may have backdated the security interests to predate the FDIC's takeover of the bank. The court observed that "Mr. Erwin may well have fraudulently created and back-dated the lien documents at issue," but "conclude[d] that it would not be appropriate to make a ruling on this issue without ... an evidentiary hearing." CLC timely appeals.

II.

Although it objects to numerous aspects of the district court's decisions, CLC adequately develops only three issues for our review: (1) the applicability of D'Oench and § 1823(e)(1) to its claim for attorneys' fees; (2) the district court's exclusion of the retainer agreement as a discovery sanction; and (3) the court's conclusion that CLC's security interests were granted in contemplation of the bank's insolvency.1 The district court had federal-question jurisdiction to hear this suit against the FDIC under 12 U.S.C. § 1819(b)(2)(A), and we exercise appellate jurisdiction under 28 U.S.C. § 1291.

III.

We review de novo both the grant of summary judgment and legal issues concerning D'Oench and related statutory provisions. Nat'l Enters., Inc. v. Smith, 114 F.3d 561, 563 (6th Cir.1997); E.I. du Pont de Nemours & Co. v. FDIC, 32 F.3d 592, 595 (D.C.Cir.1994).

A. The Development of D'Oench & Its Statutory Analogues

The Supreme Court first articulated the so-called D'Oench doctrine in a 1942 case involving a failed bank's lending practices. The FDIC sought to collect on a demand note held by the newly insolvent bank, and the bond salesman who issued the note objected, contending that the bank secretly promised not to collect on the note. D'Oench, 315 U.S. at 454, 62 S.Ct. 676. Drawing upon the criminal penalties imposed under the Federal Reserve Act, the Supreme Court recognized a "federal policy... to protect [the FDIC] ... from misrepresentations made to induce or influence the action of [the FDIC], including misstatements as to the genuineness or integrity of securities in the portfolios of banks which it insures or to which it makes loans." Id. at 459, 62 S.Ct. 676. The Court therefore estopped the notemaker from relying on the secret promise to prevent the FDIC from collecting on the note. Id. at 461-62, 62 S.Ct. 676; see also First State Bank, 872 F.2d at 715.

Congress substantially codified the D'Oench doctrine in section 13(e) of the Federal Deposit Insurance Act of 1950, 64 Stat. 873, 889, 12 U.S.C. § 1823(e). That provision currently states:

12 U.S.C. § 1823(e)(1). Because CLC does not suggest that any of its documents satisfy the statute's substantive requirements, we direct our attention to the opening paragraph of the provision, which establishes its scope.

The Supreme Court gave some guidance on this front in Langley v. FDIC, when it held that "[a] condition to payment of a note, including the truth of an express warranty, is part of the `agreement' to which the writing, approval, and filing requirements of 12 U.S.C. § 1823(e) attach." 484 U.S. 86, 96, 108 S.Ct. 396, 98 L.Ed.2d 340 (1987). The Court rejected a narrow interpretation of the term "agreement" that would have limited it to promises to take future action, but acknowledged an additional contextual limitation in the statute's "requirement that the agreement in question `ten[d] to diminish or defeat the right, title or interest' of the FDIC in the asset." Id. at 93, 108 S.Ct. 396; see also Thigpen v. Sparks, 983 F.2d 644, 648-49 (5th Cir.1993) (concluding that, despite Langley's broad interpretation of "agreement," § 1823(e)'s contextual "modifiers," pertaining to the acquisition of an asset, applied to § 1821(d)(9)(A)). Though it had no occasion to expound upon that boundary, Langley identified two overarching purposes for the statute's documentation requirements, both pertaining to oversight of a bank's assets and lending practices:

Langley, 484 U.S. at 91-92, 108 S.Ct. 396.

Against this backdrop, Congress enacted the Financial Institution Reform, Recovery and Enforcement Act (FIRREA) of 1989, Pub.L. No. 101-73, 103 Stat. 183, which made two changes relevant to this dispute. First, FIRREA amended § 1823(e)(1) to clarify that its protection extended to assets acquired by the FDIC in its capacity as receiver. Second, it adopted a new provision, codified at 12 U.S.C. § 1821(d)(9)(A), extending § 1823(e)(1)'s protections to affirmative claims against the FDIC. With one exception not relevant here,2 that provision states: "any agreement which does not meet the requirements set forth in section 1823(e) of this title shall not form the basis of, or substantially comprise, a claim against the [FDIC]." 12 U.S.C. § 1821(d)(9)(A). This new provision takes center stage in this suit against the FDIC.

The FDIC contends that either the statutory provisions or the common-law D'Oench doctrine bars CLC's undocumented fees arrangement. Though the parties and the district court at times blur the two analyses, we review them separately. See Hall v. FDIC, 920 F.2d 334, 339 (6th Cir.1990) (concluding that § 1823(e)(1) complements, rather than displaces, D'Oench). We begin with the statutory argument adopted by the district court.

B. The FDIC's Statutory Argument

First, the FDIC argues that § 1821(d)(9)(A)'s broad "any agreement" language encompasses CLC's legal services arrangement with the bank. Unlike § 1823(e)(1), the FDIC notes, the new provision lacks language constraining its scope to agreements affecting bank assets. Compare 12 U.S.C. § 1823(e)(1) (extending to agreements that "tend[] to diminish or defeat the interest of the [FDIC] in any asset acquired by it ... as a receiver," and demanding a writing executed "contemporaneously with the acquisition of the asset"), with 12 U.S.C. § 1821(d)(9)(A) (stating that "any agreement which does not meet the requirements ... in section 1823(e) of this title shall not form the basis of ... a claim against the [FDIC]"). Yet, following the FDIC's argument to its logical conclusion, § 1821(d)(9)(A)'s documentation requirements (those incorporated from § 1823(e)(1)) would apply to any agreement of any kind, including the myriad services banks contract for in the course of business: utilities, janitorial services, landscaping, supplies, etc. That would be a considerable expansion of the traditional D'Oench doctrine and § 1823(e)(1)'s statutory protections, at least for claims against the FDIC.

The Fifth Circuit examined these problems with the FDIC's interpretation in Thigpen v. Sparks. There, the FDIC argued that the statutes barred a breach-of-warranty claim against the FDIC for misrepresentations allegedly made by the now-insolvent bank during the sale of a trust company. The court disagreed, reasoning:

Thigpen, 983 F.2d at 649.

The Seventh Circuit voiced similar concerns in John v. Resolution Trust Corp., when it declined to apply the statutes and D'Oench to bar a fraud claim related to a lending institution's sale of real property. 39 F.3d 773, 776-79 (7th Cir.1994). Noting § 1823(e)'s "require[ment of] an identifiable [bank] `asset,'" the court concluded that (i) " § 1823(e) applies only to conventional loan activities," and (ii) "the only sensible reading of § 1821(d)(9)(A) must limit its scope to the loan-related transactions covered by § 1823(e)." Id. at 776. The court worried that a broader construction of "agreement" in § 1821(d)(9)(A) "would mean that ... trade creditors could only enforce agreements with the bank against the [receiver] if the bank's board of directors had approved and recorded the deals." Id.

The FDIC offers no contrary authority extending the statutory documentation requirements to service contracts or, more generally, banks' accounts payable.3 Instead, the FDIC directs our attention to its 1997 policy statement, which disagrees with Thigpen and John. Policy Statement, 62 Fed.Reg. 5984, 5984-85 (Feb. 10, 1997). The policy statement expresses the "FDIC's view" that Congress intended for §§ 1821(d)(9)(A) and 1823(e) to "be interpreted in a manner consistent with the policy concerns underlying the D'Oench doctrine," such that "these sections bar claims that do not meet the enumerated recording requirements set forth in section 1823(e), regardless of whether a specific asset is involved." Id. at 5984 (emphasis added). It further offers a vague explanation for giving § 1821(d)(9)(A) a broader scope than § 1823(e)(1).

Id. Yet, these passages fail to identify statutory language or legislative history suggesting that Congress intended § 1821(d)(9)(A) to extend the statutory recording requirements to all agreements, regardless of their relevance to bank lending activities.

The FDIC's broad interpretation of § 1821(d)(9)(A) leaves the scope of the statutory protections to the FDIC's unfettered discretion. The policy statement's position on vendor services reflects this view, stating that:

Id. at 5986.4 Indeed, when asked at oral argument whether this approach reduces to just trust us, the FDIC readily agreed. (O.A. at 22:00-35.) The absence of objective principles to guide the application (and expansion) of D'Oench and its statutory progeny gives us pause.5

The FDIC recognizes that its policy statement receives only Skidmore deference, calibrated according to the "thoroughness evident in its consideration, the validity of its reasoning, its consistency with earlier and later pronouncements, and all those factors which give it power to persuade." S. Rehab. Grp., P.L.L.C. v. Sec'y of Health & Human Servs., 732 F.3d 670, 685 (6th Cir.2013) (quoting Skidmore v. Swift & Co., 323 U.S. 134, 140, 65 S.Ct. 161, 89 L.Ed. 124 (1944)). We find the policy statement unpersuasive in light of the evolution of the statutory provisions, the reasons stated in Thigpen and John, and Congress's willingness to leave these provisions undisturbed during the intervening twenty years.

C. The FDIC's D'Oench Argument

Pivoting to the common-law D'Oench doctrine, the FDIC asserts that this court and others have already expanded D'Oench to non-asset situations, including agreements affecting bank liabilities. See, e.g., Hall, 920 F.2d at 339 (explaining that the D'Oench doctrine "may ... be invoked even where [the] FDIC does not have `an interest in an asset'"); OPS Shopping Ctr., Inc. v. FDIC, 992 F.2d 306, 309-11 (11th Cir.1993) (collecting authority applying D'Oench to bank liabilities, and concluding that D'Oench precluded enforcement of an unrecorded letter of credit issued by the failed bank). Specifically, the FDIC directs our attention to the expansive reasoning of our decision in First State Bank, where we stated that:

First State Bank, 872 F.2d at 717 (emphases added, internal citation omitted); see also id. ("`[T]he only relevant inquiry' is whether the individual or institution lent itself `to a transaction which is likely to mislead banking authorities.'" (quoting FDIC v. Investors Assocs. X., Ltd., 775 F.2d 152, 154 (6th Cir.1985))).

Admittedly, these passages speak of D'Oench in broad terms, but they do not justify a blanket extension of D'Oench to liabilities unrelated to traditional banking activities. The issue decided in First State Bank involved the application of D'Oench to a suspect lending practice: the insolvent bank's alleged promise to repurchase loan participations it had sold to another banking entity. Id. at 709; see also id. at 716 ("If the purchasing bank could require the selling bank to repurchase the assets for full value, the purchasing bank did not assume any risk associated with the borrower's ability to repay the debt."). We actually declined the FDIC's invitation to apply D'Oench more broadly to "any undisclosed agreement which would affect a bank's financial condition to the detriment of the public," concluding that the secret buy-back agreement triggered D'Oench because it contradicted the financial records provided to the FDIC by both lending institutions. See id. at 716-17.

Further, in restating the D'Oench rule, First State Bank quotes extensively from other Sixth Circuit cases that frame D'Oench in the context of a bank's lending activities. See id. at 717-18 (quoting from Investors Assocs. X. and FDIC v. Leach, 772 F.2d 1262 (6th Cir.1985), both of which address misrepresentations made by "makers" of notes or their co-conspirators). Our later decision in Hall does likewise. See Hall, 920 F.2d at 338 ("D'Oench stands for the proposition that, in order to protect FDIC from misrepresentations as to the ... assets in the portfolios of banks which FDIC insures, secret agreements that tend to deceive banking authorities cannot be raised as a defense against FDIC when it seeks to enforce a note." (citation and internal punctuation omitted)). Thus, contrary to the district court's conclusion, our cases do not compel application of D'Oench to non-banking services purchased by the bank.6

In fact, the prevailing authority suggests otherwise. Courts have repeatedly balked at attempts to extend D'Oench beyond agreements affecting a bank's lending portfolio and investment products. See, e.g., Resolution Trust Corp., 39 F.3d at 776-78 (misrepresentation claim related to the bank's sale of real property); du Pont, 32 F.3d at 597-99 (claim that the failed bank breached fiduciary responsibilities under an expired escrow agreement); Thigpen, 983 F.2d at 649 (breach-of-warranty claims related to the insolvent bank's sale of a trust company); McGarry v. Resolution Trust Corp., 909 F.Supp. 241, 245-47 (D.N.J.1995) (claim that bank violated terms of a lease). That includes service contracts. See, e.g., E.J. Sebastian Assocs. v. Resolution Trust Corp., 43 F.3d 106, 109 (4th Cir.1994) (questioning the applicability of the D'Oench doctrine to a service contract to raise capital for the bank and remanding to the district court); FDIC v. Brodie, 602 So.2d 1358, 1360-61 (Fla.Ct. App.1992) (rejecting FDIC's attempt to apply D'Oench bar to legal services agreement).

A service contract simply differs in kind from the sort of agreements affecting bank assets and liabilities contemplated in our D'Oench cases; the service-provider performs for the bank, and the bank pays its bill. See Brodie, 602 So.2d at 1360. The FDIC fails to persuade us that service contracts threaten bank viability and impede regulatory oversight to such a degree that courts must step in with the strong medicine of D'Oench. In this case, the FDIC did not know that CLC provided services to the bank during the relevant period, and the circumstances surrounding the security interests and substantial fees billed, understandably, raised suspicion.7 But we have no reason to doubt that the FDIC can assert fraud and other fact-based defenses in disputing its liabilities for these fees.

With respect to CLC's security interests in two bank properties, the FDIC contends that CLC's liens diminish the FDIC's interest in those assets, and thus bring this case under D'Oench. The district court agreed, relying on the Eighth Circuit's decision in North Arkansas Medical Center v. Barrett, 962 F.2d 780 (8th Cir.1992). That decision, we note, adopted a much broader reading of D'Oench and §§ 1821(d)(9)(A) and 1823(e)(1) than we do. See N. Ark. Med. Ctr., 962 F.2d at 787-89 (holding that the statutory documentation requirements apply to security interests pledged by a failing financial institution as collateral for large certificates of deposit).

Regardless, CLC has not attempted to enforce the attorney liens in this case. The complaint seeks only "an order awarding it its attorney fees as invoiced plus attorney fees and costs so wrongfully incurred in this matter." CLC's appellate briefing on the security interests similarly focuses on the fees claim; the matter appears as a sub-argument of the D'Oench issues pertaining to CLC's fees claim and informs the court that CLC "is only seeking compensat[ion] for valuable services" it performed for the bank.

The existence of these disputed liens does not convert CLC's straightforward contract claim for fees into the sort of secret agreement affecting bank assets and liabilities covered by D'Oench. CLC avers that the bank executed the security interests in November 2009, toward the end of the period of disputed legal services and just before the FDIC takeover. It therefore appears to present an agreement separate from the fee-deferral. Further, as we understand it, the alleged liens constitute a contingent remedy, available only if CLC prevails on the merits of its fees claim and the FDIC then defaults. Even then, CLC would need to demonstrate the legitimacy of the liens in the face of the FDIC's fraud allegations — something Erwin acknowledged during oral argument. Given the uncertain procedural posture of the security-interest claim, the contingent nature of the remedy, and the sparse briefing of these issues, we decline to address any remaining statutory or D'Oench issues at this time.

D. The Stricken Retainer Agreement

Our conclusion that neither D'Oench nor the statutory documentation requirements applies to CLC's claims for legal fees relieves CLC of the obligation to produce a written agreement by the bank for the payment of fees. Because CLC does not rely on the stricken 1989 retainer agreement for either the hours or rates billed in 2008 and 2009, or any other material issue, the discovery-sanction issue has become moot.

IV.

Finally, we address the district court's alternative conclusion holding the attorney liens unenforceable under 12 U.S.C. § 1821(e)(12) because they "were taken in contemplation of the Bank's insolvency." The court premised its ruling on two facts: (i) Erwin's alleged execution of the security interests five days before the bank was put into receivership, and (ii) the bank's understanding that CLC would defer collecting fees until the bank's financial condition improved. The FDIC's briefing adds nothing to this account, other than its assertion that Erwin may have backdated the lien documents. A reasonable factfinder may well agree that this sequence of events demonstrates that the bank executed the security interests in expectation of its demise. But, in the absence of additional evidence demonstrating the parties' actual or constructive knowledge of the bank's financial situation, the temporal proximity of the security interests to the FDIC takeover does not suffice for ruling on this issue as a matter of law. Cf. Pearson v. Durell, 77 F.2d 465, 466-68 (6th Cir.1935) (granting judgment to bank's receiver, where the record established that a bank director retrieved funds from the failing bank the day before its liquidation, at a time when the bank "had neither the money nor any assets on which it could obtain money to meet its obligations").

V.

For these reasons, we REVERSE the district court's judgment and remand for further proceedings consistent with this opinion.