Patents

K-fee v. Nespresso: How an Ambiguous Foreign File Wrapper Failed to Shrink a Claim

The Federal Circuit reversed a claim construction that read 'barcode' to exclude bit codes, holding that K-fee's statements to the European Patent Office were too ambiguous to disclaim the term's full ordinary meaning.

March 14, 2026
Coffee capsules on a machine tray beside an espresso cup
The patents covered coffee-machine capsules whose 'barcode' tells the machine how to brew — and the case turned entirely on what that word means. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

K-fee System GmbH v. Nespresso USA, Inc., No. 2022-2042 (Fed. Cir. Dec. 26, 2023), is a claim-construction decision in the purest sense: nothing about infringement, validity, or damages survived once the meaning of a single term was settled, and the entire judgment below fell with it. The patents — owned by K-fee and directed to coffee-machine portion capsules bearing a “barcode” that tells the machine how to brew — were litigated in the Central District of California, where the district court construed “barcode” to exclude so-called “bit codes” and then granted Nespresso summary judgment of noninfringement on the strength of that construction. A Federal Circuit panel of Judges Taranto, Clevenger, and Stoll, with Judge Taranto writing, reversed. The court held that K-fee’s statements during foreign prosecution were “decidedly ambiguous” and therefore could not work the clear, unmistakable disclaimer the district court had found, so the “full scope of the ordinary meaning” of “barcode” must apply. The case is a clean illustration of two enduring lessons: claim construction is the whole ballgame, and prosecution-history disclaimer is a demanding doctrine that ambiguity defeats.

At a glance

  • Case: K-fee System GmbH v. Nespresso USA, Inc., No. 2022-2042 (Fed. Cir.)
  • Decided: December 26, 2023; panel of Taranto, Clevenger, and Stoll; opinion by Judge Taranto
  • Patents: Coffee-capsule patents (the K-fee family includes U.S. Patent Nos. 10,858,176, 10,858,177, and 10,870,531) reciting a capsule with a “barcode” controlling brewing parameters
  • Disputed term: “barcode” — specifically, whether its ordinary meaning excludes “bit codes” composed of only two binary symbols (wide and narrow, or bars and gaps)
  • District court: Construed “barcode” to exclude bit codes, relying on K-fee’s European Patent Office submissions distinguishing the Jarisch reference; granted Nespresso summary judgment of noninfringement
  • Holding: Reversed and remanded; K-fee’s EPO statements were too ambiguous to constitute a clear and unmistakable disavowal, so the full ordinary meaning of “barcode” governs

When one word decides the case

The architecture of K-fee is worth pausing on because it explains why claim construction so often functions as the dispositive event in patent litigation rather than a preliminary skirmish. The accused Nespresso capsules carried what the parties agreed was a code of the two-symbol, “bit code” variety. If “barcode” reached such codes, infringement was at least viable; if it did not, K-fee lost outright. There was no factual dispute that had to go to a jury once the term was fixed — the construction was the merits. That is the recurring pattern Markman v. Westview Instruments, 517 U.S. 370 (1996), set in motion when it assigned claim construction to the court as a question of law: by front-loading the decisive interpretive question, Markman makes the construction ruling the moment most cases are won or lost, and summary judgment frequently follows mechanically.

The district court’s construction excluded bit codes, and summary judgment of noninfringement followed exactly that way. So the appeal was not really about coffee capsules. It was about whether the intrinsic record — and in particular statements K-fee made to a foreign patent office that later entered the U.S. file — narrowed a term that, on its face, was broad enough to cover the accused product.

Reading the term through Phillips, not through hindsight

The Federal Circuit’s analysis runs on the familiar framework of Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc). Phillips instructs that claim terms carry the ordinary and customary meaning they would have to a person of ordinary skill in the art at the time of invention, read in light of the specification and the prosecution history. Critically, Phillips establishes a hierarchy: the intrinsic evidence — the claims, the specification, and the prosecution history — is the primary and most reliable guide, while extrinsic evidence such as dictionaries, treatises, and expert testimony is secondary and may not be used to contradict an unambiguous intrinsic record.

The default under Phillips is the full ordinary meaning of a term. A patentee can depart from that default in only two well-defined ways: by acting as its own lexicographer and clearly redefining a term, or by clearly and unmistakably disavowing claim scope during prosecution. Both exits demand clarity. The lexicography exception requires a definition set out with reasonable clarity, deliberateness, and precision; the disavowal exception requires a disclaimer that is “clear and unmistakable.” Where the patentee has done neither with the requisite clarity, the term keeps its full ordinary breadth — which here meant a “barcode” capacious enough to include bit codes.

The district court’s error, in the panel’s telling, was to let an ambiguous record do work that only an unambiguous one can do. It treated K-fee’s distinguishing statements as if they narrowed the term, when Phillips and its disavowal line of cases reserve that effect for statements that leave no genuine doubt about what was surrendered.

A foreign file wrapper as intrinsic evidence — and its limits

The most distinctive feature of K-fee is that the disclaimer the district court found was rooted not in the U.S. prosecution as such but in statements K-fee made to the European Patent Office. Those statements became part of the U.S. intrinsic record because K-fee submitted the EPO materials to the U.S. examiner; once in the file wrapper, they were fair game for construction. The district court read K-fee’s EPO arguments distinguishing the Jarisch reference as conceding that a “barcode” must have bars of varying width and therefore could not be a mere two-symbol bit code.

The Federal Circuit declined to announce any categorical rule about whether and when statements to a foreign patent office can disclaim U.S. claim scope. It did not need to. Even assuming the EPO statements counted as ordinary intrinsic evidence, the court found them insufficient to disavow anything because, read in full, they were ambiguous. The district court, the panel observed, had relied on a partial reading; it credited isolated phrases while ignoring other EPO statements that undercut the supposed concession. K-fee’s actual point about Jarisch was that the prior-art reference did not clearly disclose bars of varying widths — not that a barcode can never be a bit code. Once the statements were read as a whole, they did not “clearly and unmistakably” tell the public that K-fee had abandoned bit-code embodiments.

This is the prosecution-history-disclaimer doctrine doing precisely what it is supposed to do. The doctrine exists to protect the public’s reliance on representations a patentee makes to secure issuance, holding the patentee to scope-narrowing concessions made to the office. But because it cuts against the claim’s ordinary meaning, it is policed by a high clarity threshold: the prosecution history “often lacks the clarity of the specification and thus is less useful for claim construction purposes,” as Phillips itself cautioned. Ambiguous prosecution statements do not narrow claims. K-fee applies that principle to a foreign file wrapper and reaches the unsurprising result that a muddled disavowal is no disavowal at all.

Open questions

The opinion deliberately leaves the threshold question unresolved: under what circumstances, if any, do statements to a foreign patent office bind a U.S. patentee as prosecution-history disclaimer? Because the court resolved the case on ambiguity, district courts confronting clear foreign concessions still lack a definitive Federal Circuit rule on whether to treat them as disclaiming intrinsic evidence or merely as extrinsic context. A second open question is practical: how much of a foreign file wrapper must a court read before finding disclaimer? K-fee faults the district court for a selective reading but does not specify how “whole-record” the inquiry must be. Finally, the decision leaves room to argue, in future cases, whether translated foreign-office statements should carry the same disclaiming force as native English prosecution remarks given the interpretive slippage translation can introduce.

Implications

  • Claim construction remains the case. Where the accused product’s character is undisputed, the construction ruling decides infringement; litigants should treat the Markman phase as the merits, not a preliminary.
  • Disclaimer is defeated by ambiguity. A party urging prosecution-history disclaimer must show a clear, unmistakable surrender read against the entire record, not a favorable phrase pulled from context.
  • Foreign prosecution can follow you home. Submitting EPO or other foreign-office materials to the USPTO pulls them into the intrinsic record; what counsel argues abroad can be cited in U.S. claim construction.
  • Read the whole file wrapper. Both sides should marshal the complete prosecution narrative; selective quotation invites reversal, as it did here.
  • Patent drafters should mind cross-border consistency. Coordinated argument strategies across the EPO and USPTO reduce the risk that an overseas concession is later weaponized at home.

Frequently asked questions

What did the Federal Circuit actually decide about “barcode”? That its full ordinary meaning applies and is broad enough to include “bit codes” of two binary symbols. The district court’s narrower construction excluding bit codes was reversed because the foreign-prosecution statements it relied on were too ambiguous to disclaim that scope.

Can statements to the European Patent Office narrow a U.S. patent claim? The court did not adopt a categorical rule. It assumed such statements could be relevant intrinsic evidence here because K-fee had filed them with the USPTO, but it held that these particular statements were ambiguous and so disclaimed nothing. The broader question remains open.

Why does ambiguity matter so much for prosecution-history disclaimer? Because disclaimer overrides a term’s ordinary meaning and the public relies on the claim’s apparent scope, the Federal Circuit requires any disavowal to be “clear and unmistakable.” A statement open to more than one reasonable reading cannot meet that standard and therefore does not narrow the claim.

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