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Federal Circuit Holds That A Claim Covering A Scientific Impossibility Is Not Indefinite, But Is Not Enabled
10/06/2026On October 1, 2026, the U.S. Court of Appeals for the Federal Circuit affirmed the District Court for the District of Delaware’s judgment invalidating claims 1, 11, and 18 of U.S. Patent No. 6,711,385 (“the ’385 Patent”), but on enablement grounds rather than the indefiniteness grounds that were the subject of the appeal. Satius Holding, LLC v. Samsung Electronics Co., Ltd., No. 2025-1446 (Fed. Cir. Oct. 1, 2026).
The ’385 patent covers a communications apparatus with a coupler that matches a transmitter's output impedance to the characteristic impedance of the air. Claim 1 recites an apparatus “for transmitting electric or electromagnetic signals over air.” In 2018, plaintiff sued defendants, and the district court stayed the case pending ex parte reexamination. The USPTO rejected independent claim 1, but confirmed the patentability of dependent claims 11 and 18. After the stay was lifted, the district court, following claim construction, held all three claims indefinite because transmitting electric signals over air is a scientific impossibility.
On appeal, the Federal Circuit first agreed with the district court that claim 1 covers two kinds of signals, and that transmitting the first (electric) kind over air is, as the parties agreed, impossible. Plaintiff argued that the language really describes an electric signal that is converted into an electromagnetic signal, which then travels over the air. The court rejected that reading. Transmitting signals “over” the air is not the same as communicating them “to” the air, as the claim separately recites, and plaintiff’s reading would require either construing different terms in the body of the claim with the same meaning or adding a conversion step that appears nowhere in the claim and would not apply equally to both signal types. Courts “may not redraft claims” to make them operable or to sustain their validity.
The court nonetheless held that impossibility does not always make a claim indefinite. The test under Nautilus is whether the claim informs skilled artisans of its scope with reasonable certainty, and “indefiniteness is not the same as impossibility.” An invention’s operability “may say nothing” about whether a skilled artisan understands the claim's bounds. The court acknowledged that it has held some impossible claims indefinite, and that a claim may be so nonsensical that a skilled artisan would struggle to understand its bounds. But it distinguished Synchronoss v. Dropbox, where the claims were nonsensical and the specification showed they did not reflect what the inventor regarded as the invention. Here, the impossible language appears in both the claims and the written description, and defendants themselves argued the claim “unmistakably” covers the impossibility. The court also discounted defendants’ expert testimony as conclusory and inconsistent with that position, and rejected any “per se rule” that a claim with one impossible permutation is indefinite.
The district court expressed doubt that the full scope of claim 1 could be enabled, but it declined to decide that issue. Defendants had raised enablement only in a footnote in their initial claim construction briefing (pre-stay), and the district court held that arguments made only in a footnote were waived or forfeited. But the Federal Circuit exercised its discretion to decide the issue in the first instance, finding the parties had fully briefed the issue on appeal; it was a pure question of law on undisputed facts, and remand would serve no purpose.
Under Amgen v. Sanofi, a specification must enable the full scope of the claim. The court held that that standard “cannot possibly be met” where an express claim limitation adds inoperable embodiments to the claim's scope. It relied on Liebel-Flarsheim and on EMI Group, which held that, when an impossible limitation is clearly embodied in a claim, the claimed invention must be held invalid. Because claim 1 expressly covers transmitting electric signals over air, a category that no skilled artisan could make or use, the court concluded that “the more one claims, the more one must enable,” and that these claims “fall woefully short.”
In a separate nonprecedential opinion issued the same day, the court dismissed as moot the patent owner’s appeal from the PTAB's obviousness rejection of claim 1 in the reexamination, in light of the invalidity ruling. In re Satius Holding, Inc., No. 2025-1444 (Fed. Cir. Oct. 1, 2026).
This decision clarifies the line between two doctrines that challengers often blur together. A claim that covers an impossible or inoperable embodiment is not necessarily indefinite for that reason alone. The question under § 112(b) is whether the claim conveys its scope with reasonable certainty, and the court left room for indefiniteness where a claim is so nonsensical that a skilled artisan could not tell what it covers, as in Synchronoss. But, where, as here, the claim and specification both recite the impossible language and the scope is clear, the challenge belongs under § 112(a). In, there, Amgen's full-scope requirement is difficult to satisfy when a claim expressly recites an inoperable alternative, and courts will not rewrite claims to save them. The court's willingness to decide enablement for the first time on appeal also underscores the importance of preserving and fully briefing the issue at every stage.
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