Third Circuit: Arbitrators May Clarify an Ambiguous Interim Liability Award Under the Functus Officio “Ambiguity Exception,” Even When Damages Remain Open

I. Introduction

In Prospect Capital Management L.P. v. Stratera Holdings, LLC; Destra Capital Managers LLC (3d Cir. Aug. 4, 2026), the Third Circuit addressed when an arbitral panel—after issuing an “Interim Award” resolving liability—may issue a “revised” interim award clarifying the scope of that liability without violating the functus officio doctrine. The dispute arose from a contract governing how administrative fees would be split among co-participants in the Priority Income Fund, specifically whether “DRIP” (dividend reinvestment program) shares should be included in fee calculations and whether the award covered DRIP shares tied to both Destra’s sub-wholesaling period and Provasi’s earlier wholesaling period.

Prospect challenged the revised award in federal court under FAA vacatur standards, arguing the panel had impermissibly revisited the merits. The District of Delaware confirmed the award; the Third Circuit affirmed, holding the clarification fit the ambiguity exception to functus officio, and resolving threshold issues about award finality and the continued vitality of functus officio after Morgan v. Sundance.

II. Summary of the Opinion

The Third Circuit held:

  • Finality (for functus officio): An interim award that finally resolves liability is “final” as to that issue even if damages remain to be calculated; functus officio can attach to that partial final determination.
  • Functus officio remains good law: Morgan v. Sundance does not abrogate functus officio because the doctrine is a longstanding common-law rule specific to arbitration, not an arbitration-favoring tweak to a generally applicable procedural rule.
  • Ambiguity exception applies: The “Interim Award” was susceptible to more than one interpretation about which DRIP shares were covered; the panel’s revised interim award was a permissible clarification rather than an impermissible redetermination of the merits.
  • Deference amplified by AAA Rules: By adopting AAA Rule 9 (authorizing arbitrators to interpret and apply the rules governing their powers) and AAA Rule 52 (limiting re-determination of merits), the parties delegated substantial authority to the panel to apply the functus officio framework; courts therefore owed broad deference under FAA § 10(a)(4) standards.

III. Analysis

A. Precedents Cited

1. Third Circuit functus officio framework and exceptions

  • Verizon Pa. LLC v. Commc'ns Workers of Am., AFL- CIO, Loc. 1300: The central modern Third Circuit authority. The court reiterated functus officio’s baseline bar on revisiting merits after issuance of a final award, confirmed the three exceptions, and—critically here—held that an award resolving liability can be final for functus officio purposes even if “ancillary” remedy issues remain. The court used Verizon both to (i) reject the argument that the interim liability award lacked finality and (ii) guide how to examine ambiguity by reading the “Award” alongside the accompanying opinion.
  • Office & Pro. Emps. Int'l Union, Loc. No. 471 v. Brownsville Gen. Hosp.: Quoted for the doctrine’s rationale—arbitrators’ susceptibility to outside influence and the ad hoc nature of tribunals—supporting why post-award changes are constrained absent a recognized exception.
  • Colonial Penn Ins. Co. v. Omaha Indem. Co.: Used to (i) describe functus officio’s policy concerns and (ii) narrow the “mistake on the face of the award” exception to clerical/arithmetic-type errors, preventing backdoor merits relitigation.
  • La Vale Plaza, Inc. v. R.S. Noonan, Inc.: Cited for the principle that functus officio applies to a “final award,” framing the threshold finality dispute.

2. Supreme Court and deference to arbitral interpretation

  • Sutter v. Oxford Health Plans LLC (and the Supreme Court affirmance cited in the opinion): Provided the governing deference standard under FAA § 10(a)(4): if the arbitrator is even arguably construing/applying the contract, the award stands. The Third Circuit leveraged this principle to uphold the panel’s clarification as a rational interpretive act within delegated authority.
  • United Steelworkers of Am. v. Enter. Wheel & Car Corp.: Cited for the distinction between ambiguity in an accompanying opinion (not necessarily dispositive) and ambiguity in the award itself. The Third Circuit applied this to reject Prospect’s attempt to treat the “Holding” subsection as the “award” in isolation.

3. Clarifying “ambiguity” and interpretive method

  • Gen. Re Life Corp. v. Lincoln Nat'l Life Ins. Co., quoting Sterling China Co. v. Glass, Molders, Pottery, Plastics & Allied Workers Loc. No. 24: Provided a workable definition: an award is ambiguous if it fails to address a later-arising contingency or is susceptible to more than one interpretation. The Third Circuit adopted this “susceptible to more than one interpretation” approach to validate clarification.
  • Pennsylvania v. Brown, citing Bingham v. United States: Used for an adjudicatory presumption: issues clearly presented to a tribunal may be treated as covered by its decision even if not explicitly discussed. This helped support the conclusion that the scope question (Provasi-related DRIP shares) could reasonably be seen as included, contributing to ambiguity.
  • Additional persuasive authorities in the opinion’s discussion: United Steelworkers of Am., Loc. 4839 v. New Idea Farm Equip. Corp. and Int'l Ass'n of Machinists & Aerospace Workers v. San Diego Marine Constr. Corp., reinforcing that courts should not demand perfectly unambiguous arbitral opinions, lest arbitrators stop writing explanations.

4. Finality doctrines and judicial review timing

  • PG Publ., Inc. v. Newspaper Guild of Pittsburgh: Invoked by Stratera to argue an arbitration is not “final” for review if remedy remains open. The Third Circuit rejected importing that “complete arbitration rule” standard into functus officio analysis because Verizon already held that issue-by-issue finality is sufficient for functus officio to attach.

5. FAA jurisdictional background and common-law retention

  • Badgerow v. Walters: Cited on subject-matter jurisdiction principles, confirming diversity jurisdiction as the basis here.
  • Morgan v. Sundance: The court addressed, and rejected, the argument that Morgan undermined functus officio.
  • United States v. Texas: Cited for the presumption that statutes do not displace longstanding common-law principles absent clear indication—supporting the continued vitality of functus officio.
  • Bayne v. Morris: Cited to show historical pedigree for functus officio in U.S. law.

B. Legal Reasoning

1. The court’s analytical sequence: threshold issues first

The Third Circuit treated two arguments as threshold: (1) whether the interim award was “final” for functus officio purposes, and (2) whether functus officio survived Morgan v. Sundance. Only after resolving those did it reach the ambiguity exception.

2. Finality of an interim liability award

Following Verizon Pa. LLC v. Commc'ns Workers of Am., AFL- CIO, Loc. 1300, the court held that functus officio attaches once a tribunal finally resolves a submitted issue—even if other issues (like damages) remain. Because the “Interim Award” here granted some relief, dismissed other claims, and contemplated reopening only for damages/fees calculations, it was final as to liability. The court refused to equate functus officio finality with the “complete arbitration rule” finality from PG Publ., Inc. v. Newspaper Guild of Pittsburgh, emphasizing different purposes and contexts.

3. Functus officio after Morgan

The court distinguished Morgan v. Sundance: Morgan barred courts from inventing arbitration-favoring variants of generally applicable procedural rules (e.g., waiver). Functus officio, by contrast, is an arbitration-specific common-law doctrine with deep historical roots, not a pro-arbitration distortion of an existing federal procedural rule. Accordingly, the FAA’s text and Morgan’s reasoning did not displace it.

4. Ambiguity exception: what was ambiguous, and why the revision was a clarification

The core dispute was whether the interim decision covered DRIP shares only for Destra’s sub-wholesaling period or also DRIP shares tied to Provasi’s earlier wholesaling period. Prospect emphasized the “Holding” section’s reference to shares “for which [Destra] served as sub-wholesaler” and the dismissal of “all other claims.” But the court identified countervailing signals:

  • The Provasi-DRIP issue was squarely presented to the panel (supporting an inference it was decided even if not crisply stated).
  • The opinion repeatedly referenced “claimants” and “DRIP shares” generally, not strictly Destra-issued DRIP shares.
  • The panel’s reliance on Schedule 11.18’s example and pre–May 11, 2018 share references could naturally encompass Provasi-era shares.

Crucially, the court framed the relevant ambiguity as ambiguity in the “award” as a whole, not merely in the narrative reasoning. Mirroring Verizon, it treated the dispositional “Interim Award” section (referring to “above-described DRIP Shares”) as the operative award language, and then looked to the accompanying opinion to determine what those “above-described” shares were. Because both parties’ readings were reasonable, the award was “susceptible to more than one interpretation,” fitting the ambiguity exception. The revised interim award therefore operated as a permissible clarification rather than an impermissible merits redetermination.

5. Contractual delegation via AAA Rules and FAA § 10(a)(4) deference

The court emphasized that the contract incorporated AAA rules: AAA Rule 52 (no re-determination of merits) and AAA Rule 9 (arbitrator may interpret and apply the rules governing the arbitrator’s powers and duties). That incorporation meant the parties “bargained for” the functus officio constraint and also delegated interpretive authority over its boundaries to the panel. Under Sutter v. Oxford Health Plans LLC, the court’s role was narrow: absent an arbitrator stepping outside delegated authority, a rational clarification must stand even if a court might prefer a different reading.

C. Impact

  • Clarifications are safer when the award text is referential: Where a dispositive “Award” section incorporates descriptions from the opinion (e.g., “above-described” categories), post-award disputes over scope will more readily qualify as “ambiguity,” permitting clarification.
  • Interim liability awards can “lock in” scope early: Parties should treat interim liability determinations as final for functus officio purposes. A party dissatisfied with scope should raise it promptly as an ambiguity issue rather than assuming damages proceedings keep the tribunal freely revisable.
  • AAA Rule 9 may strengthen arbitrators’ control over functus officio questions: Incorporating AAA rules can increase judicial deference to how arbitrators characterize post-award action (clarification vs. redetermination), raising the premium on careful drafting and on requesting explicit dispositive language.
  • Morgan v. Sundance is not a general attack on arbitration common law: The decision signals Morgan’s limit: it restrains arbitration-favoring procedural “special rules,” not historically rooted arbitral doctrines like functus officio.

IV. Complex Concepts Simplified

  • Functus officio: Literally “having performed one’s office.” In arbitration, it generally means that once arbitrators issue a final decision on an issue, they cannot revisit the merits of that decision.
  • FAA § 10(a)(4): A narrow ground for vacating an award: arbitrators “exceeded their powers” or failed to issue a “mutual, final, and definite” award on the submitted matter. It does not authorize courts to correct legal or factual errors.
  • Ambiguity exception (to functus officio): If an award is reasonably susceptible to more than one interpretation, arbitrators may clarify what they meant—without changing the merits.
  • Interim award vs. final award: “Interim” often means damages or fees are still to be calculated. But the liability determination can still be “final” as to liability, triggering functus officio limits and exceptions for that issue.
  • Complete arbitration rule: A doctrine about when courts will review arbitration (often requiring the arbitration be complete as to liability and remedy). The Third Circuit held this is different from when functus officio attaches (which can be issue-by-issue).

V. Conclusion

The Third Circuit’s decision establishes and reinforces a practical rule for arbitration in the circuit: an interim award that finally resolves liability is final for functus officio purposes, and where the award is reasonably susceptible to multiple interpretations, an arbitral panel may issue a clarifying revision under the ambiguity exception. The court also confirms that functus officio remains viable after Morgan v. Sundance and underscores that incorporation of AAA Rules—especially AAA Rule 9—can expand arbitral discretion over the doctrine’s application, leaving reviewing courts with a highly deferential FAA § 10(a)(4) role.