Jurisdiction-If-We-Win: T-Mobile v. KAIFI and the Gunn Boundary Line

by Dennis Crouch

The Federal Circuit heard oral argument this week in T-Mobile US, Inc. v. KAIFI LLC, No. 25-1006 (Fed. Cir. argued May 5, 2026), and most of the forty minutes were spent on the question: does the Federal Circuit even have jurisdiction over this appeal? (Listen on my ScotusGate site)

The underlying dispute is a Texas-law breach-of-contract case. T-Mobile and KAIFI settled patent infringement litigation on the eve of trial in the Eastern District of Texas. The settlement called for an upfront payment plus a contingent payment if any "Asserted Claim survives the [ex parte reexamination] EPR" then pending before the Patent Office. Although the USPTO confirmed several claims as patentable without amendment, T-Mobile refused to make the contingent payment, contending that KAIFI's positions before the examiner had narrowed the claims through prosecution disclaimer and that KAIFI's failure to disclose contradictory district-court filings rendered the patent unenforceable through inequitable conduct. Judge Gilstrap rejected those arguments and entered judgment for KAIFI for breach of contract.

The jurisdictional question matters because the case landed in the wrong court twice. T-Mobile's notice of appeal designated the Federal Circuit, but a "clerical error" sent the appeal to the Fifth Circuit, which transferred it to the Fed.Cir. on T-Mobile's unopposed motion. KAIFI then moved to transfer back, arguing that the contract claim does not arise under the patent laws. The motions panel deferred the question to the merits panel.  And then KAIFI changed its position. In its merits brief, KAIFI ultimately agreed that the Federal Circuit has jurisdiction, but only if the Court adopts KAIFI's preferred reading of the contract term "survives." T-Mobile's reply brief calls this a "jurisdiction-if-we-win-but-not-if-we-lose" argument. The oral arguments got into the "trying to have it both ways" argument and Judge Taranto pressed Philip Warwick (KAIFA's counsel) on the strangeness of conditioning jurisdiction on a particular merits resolution.

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