Forum-Selection Clause “Applicability” Is Governed by the Contract’s Substantive Law; “Enforceability” Remains Federal

I. Introduction

Declan Flight, Inc. v. Textron eAviation, Inc. (11th Cir. May 26, 2026) arises from the rapid unwinding of two U.S. aviation sales relationships after Textron, Inc. acquired Slovenian aircraft manufacturer Pipistrel. Plaintiffs Declan Flight, Inc. (an Arizona aviation-management firm) and Right Rudder Aviation, LLC (“RRA,” a Florida aerospace services firm) alleged that Textron, Inc. and its subsidiary Textron eAviation, Inc. tortiously interfered with:

  • Declan’s sales-representative contract with Pipistrel Vertical Solutions d.o.o. (Count I),
  • RRA’s exclusive distribution contract with Pipistrel and Pipistrel Italia S.r.l (Count II), and
  • RRA’s signed aircraft sales contract with Mesa Airlines (Count III).

The central appellate issues were:

  • Whether the district court correctly used Atlantic Marine Construction Co. v. U.S. District Court for the Western District of Texas’s modified forum non conveniens framework after allowing non-signatories (Textron/eAviation) to invoke Slovenian forum-selection clauses via federal equitable estoppel.
  • Whether personal jurisdiction existed over Textron/eAviation on Count III under Florida’s long-arm statute, and whether the district court could reach the merits without a correct jurisdictional basis.

II. Summary of the Opinion

The Eleventh Circuit:

  1. Reversed dismissal of Counts I and II for forum non conveniens, holding that the “applicability/scope” of a forum-selection clause (including whether a non-signatory can invoke it) is a contract-interpretation question governed by the substantive law governing the contract, while enforceability remains governed by federal common law (The Bremen). Because Slovenian law governed the contracts and did not allow these non-signatory defendants to invoke the clauses, there was no “valid forum-selection clause” applicable to plaintiffs’ claims, and Atlantic Marine’s modified test should not have been used.
  2. Reversed the district court’s finding of personal jurisdiction as to Count III, concluding the district court relied on incorrect grounds under Florida’s long-arm statute (and the Mesa Contract’s forum-selection clause could not supply consent as to non-parties). Because personal jurisdiction was not properly established, the district court could not reach the merits; on remand, jurisdiction must be analyzed correctly (potentially under the “tortious act” prong).
  3. Remanded for further proceedings.

III. Analysis

A. The New Rule: Two-Step Analysis—Applicability Under Substantive Contract Law; Enforceability Under Federal Common Law

The opinion draws a sharp doctrinal line that the Eleventh Circuit had not previously made explicit:

  • Step 1 (Applicability / Scope): interpret the forum-selection clause like any other contract term, using the substantive law governing the contract (which may be foreign law). This includes questions such as whether the clause covers the claims, is mandatory or permissive, and—critically here—whether a non-signatory may invoke it.
  • Step 2 (Enforceability / The Bremen): if the clause applies, assess whether it should be enforced under federal common law principles (fraud/overreaching, deprivation of day in court, deprivation of remedy, or contravention of public policy).

This matters because Atlantic Marine’s modified forum non conveniens approach only “kicks in” when an applicable and enforceable forum-selection clause reaches the claims at issue. Without applicability, the district court must apply the traditional forum non conveniens balancing test, including private-interest factors and the usual burden on the defendant.

B. Precedents Cited (and How They Shaped the Decision)

1. Forum-selection clause enforcement and forum non conveniens

  • Atlantic Marine Construction Co. v. U.S. District Court for the Western District of Texas: The district court applied its “modified” approach—treating private-interest factors as entirely favoring the chosen forum and shifting the burden to the plaintiff. The Eleventh Circuit limited Atlantic Marine to cases where a forum-selection clause is actually applicable to the dispute and parties.
  • M/S Bremen v. Zapata Off-Shore Co. (The Bremen): The court reaffirmed that federal common law governs whether an applicable clause is enforceable (unreasonable/unjust, invalid for fraud/overreaching, etc.), but emphasized that The Bremen does not answer antecedent questions of scope/applicability.
  • AQuate II LLC v. Myers, Fresh Results, LLC v. ASF Holland, B.V., Tazoe v. Airbus S.A.S., Kolawole v. Sellers, Leon v. Millon Air, Inc.: These cases supplied the Eleventh Circuit’s baseline forum non conveniens framework and clarified when Atlantic Marine alters it. The opinion uses AQuate to underscore the “calculus changes” only with an applicable clause.

2. The equitable estoppel path the district court took (and why it failed)

  • Bahamas Sales Assoc., LLC v. Byers and MS Dealer Serv. Corp. v. Franklin: These stand for federal equitable estoppel principles sometimes allowing nonsignatories to enforce contract provisions (commonly in arbitration contexts and sometimes in forum-selection disputes). The district court relied on them to let Textron/eAviation invoke the Slovenian forum clauses. The Eleventh Circuit held the district court asked the wrong choice-of-law question: whether equitable estoppel is available is part of scope/applicability, which must be decided under the contract’s governing substantive law (here, Slovenian law), not federal common law.

3. Erie, contract interpretation, and the “scope” of clauses

  • Erie R. Co. v. Tompkins, Garcia v. Chiquita Brands Int'l, Inc., Gasperini v. Ctr. for Humans., Inc.: These undergird the court’s classification of contract interpretation as substantive for Erie purposes and justify applying state (or foreign) substantive law absent countervailing federal interests.
  • AFC Franchising, LLC v. Purugganan, Fernandez v. Bankers Nat'l Life Ins.: Cited for the proposition that contract interpretation issues are substantive and state-law-governed in the Eleventh Circuit.
  • Firexo, Inc. v. Firexo Grp. Ltd., Collins v. Mary Kay, Inc., Weber v. PACT XPP Techs., AG, Martinez v. Bloomberg LP, Yavuz v. 61 MM, Ltd., Albemarle Corp. v. AstraZeneca UK Ltd., Manetti-Farrow v. Gucci Am., Inc.: The opinion situates itself in an explicit circuit split and adopts the approach reflected in Firexo, Martinez, Weber, Yavuz, and Collins: interpretive questions are governed by contract law, not federal common law. The Eleventh Circuit thus aligns with the “growing trend” recognizing the applicability/enforceability distinction.

4. Arbitration analogies: who can enforce agreement terms

  • Arthur Andersen LLP v. Carlisle and Lawson v. Life of the S. Ins. Co.: The court imported a well-settled arbitration principle: whether nonparties can enforce contract provisions (including via “estoppel”) is governed by traditional principles of state contract law. The opinion treats foreign forum-selection clauses as a cousin of arbitration clauses, reinforcing that “who is bound” is a substantive contract question.
  • Vimar Seguros y Reaseguros, S.A. v. M/V Sky Reefer: Cited for the proposition that foreign arbitration clauses are a subset of foreign forum-selection clauses, supporting the analogy.

5. Florida choice-of-law and the “procedural” characterization debate

  • Interface Kanner, LLC v. JPMorgan Chase Bank, N.A. and Mazzoni Farms, Inc. v. E.I. DuPont De Nemours & Co.: Used to apply Florida’s general rule honoring contractual choice-of-law provisions unless they violate strong public policy—pushing the analysis toward Slovenian law.
  • Golden Palm Hospitality, Inc. v. Stearns Bank Nat'l Ass'n, Fendi S.r.l. v. Condotti Shops, Inc., Shoppes Ltd. P'ship v. Conn, Aqua Sun Mgmt., Inc. v. Divi Time Ltd.: These intermediate Florida cases labeled validity/enforceability of forum clauses “procedural” and sometimes used Florida law to decide mandatory/permissive questions. The Eleventh Circuit predicted the Florida Supreme Court would not extend that “procedural” label to contract-interpretation questions once Florida’s adoption of The Bremen and the structure of forum non conveniens are properly accounted for.
  • Manrique v. Fabbri and Garcia Granados Quinones v. Swiss Bank Corp. (Overseas), S.A.: The court relied heavily on these Florida Supreme Court decisions to forecast Florida’s approach: Florida adopted The Bremen, and Garcia Granados signaled that a chosen foreign law could matter to interpreting “may” in a forum clause—supporting the conclusion that interpretation is not purely “procedural” for Florida choice-of-law purposes.
  • Kinney System, Inc. v. Continental Insurance Company: Invoked to show Florida’s adoption of federal forum non conveniens doctrine, further supporting harmonization with a two-step framework rather than a Florida-only interpretive approach.

6. Slovenian/EU law sources on non-signatory enforcement

  • Profit Inv. SIM SpA v. Ossi: Quoted for the core EU-law idea that jurisdiction clauses rest on party consent and generally bind only parties to the contract; absent a contractual relationship, one cannot be regarded as having “agreed” to the designated court.
  • Cardel Damage Claims (CDC) Hydrogen Peroxide SA v. Evonik Degussa GmbH: Cited for the limited exception where a third party may be bound if it succeeded to the rights and obligations of an original party—an exception the court found inapplicable on the record.

C. Legal Reasoning

1. Why “applicability” must be analyzed first

The court reasoned that it is logically impossible to decide whether a clause should be enforced before determining whether the clause governs the dispute and parties at all. The enforceability framework of The Bremen concerns fairness and public policy; it does not determine who the clause covers. Scope questions require interpreting the contract’s language, which is a substantive issue.

2. Why federal common law does not govern applicability in diversity

Applying Erie, the court held that contract interpretation is “quintessentially substantive,” and no countervailing federal interest justified a federal common-law rule defining forum clause scope. Indeed, a federal rule could frustrate party expectations by expanding or narrowing the clause beyond what governing contract law would provide.

3. Choice of law: why Slovenian law governed the forum clauses’ scope

Under Florida choice-of-law principles, the parties’ selection of Slovenian law controlled absent a strong Florida public policy conflict. The court rejected the defendants’ attempt to recharacterize interpretation as part of “procedural” validity/enforceability analysis, predicting the Florida Supreme Court would treat interpretation as outside that procedural bucket given Manrique v. Fabbri, Garcia Granados Quinones v. Swiss Bank Corp. (Overseas), S.A., and Florida’s adoption of federal forum non conveniens doctrine in Kinney System, Inc. v. Continental Insurance Company.

4. Application of Slovenian/EU law: no equitable-estoppel-based non-signatory invocation

With Slovenian law governing, the key factual/legal bridge the district court used—federal equitable estoppel—collapsed. The Eleventh Circuit credited plaintiffs’ foreign-law submission that Slovenian courts (applying EU jurisdiction rules) generally require actual consent between the litigants for a jurisdiction clause to bind them, and defendants did not adequately rebut that. Therefore, Textron/eAviation could not invoke the forum clauses, meaning Atlantic Marine was inapplicable and the district court used the wrong forum non conveniens standard.

5. Count III: personal jurisdiction must precede merits

The court emphasized the sequencing requirement: jurisdiction first, merits second. The district court relied on:

  • Florida’s long-arm provision for those who “[b]reach a contract in this state by failing to perform acts required by the contract to be performed in this state,” Fla. Stat. § 48.193(1)(a)7—yet Textron/eAviation were not parties to the Mesa Contract, making that prong a poor fit.
  • The Mesa Contract’s forum-selection clause as “consent”—but that clause bound the seller and purchaser (RRA and Mesa), not these non-party defendants, and the district court did not conduct the correct statutory analysis (including Fla. Stat. § 48.193(1)(a)9).

RRA attempted to pivot on appeal to the “tortious act” prong, Fla. Stat. § 48.193(1)(a)2, but the Eleventh Circuit declined to analyze that prong in the first instance and remanded for proper consideration. Without properly established personal jurisdiction, the district court’s merits ruling could not stand.

D. Impact

1. A significant doctrinal clarification in the Eleventh Circuit (with national implications)

This decision resolves (for the Eleventh Circuit) a question it labeled one of first impression: whether federal common law governs both the “enforceability” and “interpretation/scope” of forum-selection clauses. It adopts a two-step model and joins circuits treating scope as a substantive contract question.

2. Reduced ability of non-signatories to leverage forum-selection clauses via federal equitable estoppel

The practical effect is to make non-signatory enforcement dependent on the contract’s governing law. Where contracts select foreign law (or even a particular state’s law) that does not recognize equitable-estoppel-style enforcement in this setting, non-signatories will face steeper hurdles to obtaining dismissal/transfer based on the clause.

3. Narrowing the automatic force of Atlantic Marine

District courts in the Eleventh Circuit must now ensure the clause is applicable under governing substantive contract law before applying Atlantic Marine to deem private-interest factors irrelevant and shift burdens to plaintiffs.

4. Litigation behavior: foreign-law briefing becomes outcome-determinative

The opinion underscores that foreign law can decide threshold forum questions, and that parties who fail to brief foreign law risk abandonment. Expect more aggressive use of Fed. R. Civ. P. 44.1 submissions early in litigation.

5. Personal jurisdiction discipline in tortious interference cases

On Count III, the decision reinforces that courts must identify the correct long-arm prong and cannot assume a contract’s forum clause supplies consent jurisdiction over alleged interferers who never signed (or otherwise validly consented). It also emphasizes that merits dismissals cannot stand where personal jurisdiction analysis is faulty or incomplete.

IV. Complex Concepts Simplified

  • Forum-selection clause: A contract term naming where lawsuits must be filed (e.g., “courts of Nova Gorica, Slovenia”).
  • Applicability / scope (newly emphasized): Whether the clause covers the kind of dispute and the parties in court (including whether a non-signatory can use it).
  • Enforceability (The Bremen): Even if applicable, whether enforcing the clause would be unfair or contrary to public policy (fraud, extreme inconvenience, no remedy, etc.).
  • Forum non conveniens: A doctrine allowing dismissal when another forum is substantially better suited. With an applicable clause, Atlantic Marine makes dismissal/transfer far easier; without one, courts balance private and public factors under the traditional test.
  • Equitable estoppel (in this context): A doctrine sometimes allowing a non-signatory to enforce contract terms against a signatory. This case holds that whether that doctrine can expand a forum clause to a non-signatory is governed by the contract’s substantive law, not a free-floating federal rule.
  • Erie doctrine: In diversity cases, federal courts apply state substantive law and federal procedural law. The opinion classifies forum-clause “scope” as substantive because it is contract interpretation.
  • Long-arm statute: A state statute defining when its courts can exercise jurisdiction over out-of-state defendants. A court must fit the facts into a specific statutory prong before reaching due process and then merits.

V. Conclusion

Declan Flight establishes a consequential Eleventh Circuit rule: the applicability (scope) of a forum-selection clause is governed by the substantive law governing the contract, while enforceability remains a federal common-law question under The Bremen. Applied here, Slovenian law controlled and did not allow non-signatory invocation, so Atlantic Marine’s clause-driven forum non conveniens shortcut was unavailable and Counts I and II could not be dismissed on that basis.

Separately, the court reinforced that personal jurisdiction must be correctly grounded in the forum’s long-arm statute before merits rulings can stand, reversing the jurisdiction finding on Count III and remanding for proper analysis.