Missed Signals: The Importance of Physical Plausibility in Claim Construction
SATIUS HOLDING, LLC v. SAMSUNG ELECTRONICS CO., LTD. (2025-1446, October 1, 2026)
U.S. Patent No. 6,711,385 (“the 385 patent”) relates to a coupler designed to match the impedance of a transmitter to the impedance of air. The physics problem is a familiar one in RF engineering: signals reflect and lose power when transmitting between media of mismatched impedance, so matching the transmitter’s output impedance to the air’s characteristic impedance improves signal transfer. The ‘385 patent’s claimed solution is a coupler containing a transformer with a non-magnetic core.
Claims 1, 11, and 18 were at issue in this case. Claim 1 recites “a communications apparatus for transmitting electric or electromagnetic signals over air,” with a transmitter (having an output impedance) and a coupler (containing the non-magnetic-core transformer) that both communicates those signals to the air and matches the transmitter’s output impedance to the air’s characteristic impedance. Claims 11 and 18 depend from claim 1.
The claim drafting choice that drives the entire opinion is the phrase “electric or electromagnetic signals.” Electronic communications operate by transmitting electromagnetic signals over air. Communication devices transmit electric signals between various internal components, but not over the air; it is, in the shared view of the parties, a scientific impossibility. The patent claims both, in the alternative, as if they were interchangeable options on a drop-down menu.
Procedural History
Satius sued Samsung in 2018 in Delaware, asserting claims 1, 11, and 18. The district court stayed the case pending reexamination at the PTO, which rejected claim 1 but upheld claims 11 and 18. After the stay lifted, the DC proceeded to claim construction and concluded that claim 1 (and, by extension, dependent claims 11 and 18) was indefinite under 35 U.S.C. § 112(b) because the claims literally recited transmitting electric signals over air, which is impossible. The DC entered final judgment of invalidity. Notably, the DC separately expressed skepticism that the claims were enabled, going so far as to say it struggled to see how the full scope of claim 1 could be enabled, but found the enablement argument waived and declined to rule on it, reasoning that claim construction is not typically the right time to resolve enablement issues. This reluctance proved to be only a temporary reprieve.
Satius appealed the indefiniteness ruling. Samsung defended the judgment but also urged, as an alternative ground, that the claims failed for lack of enablement even if they were definite.
Patent Preparation/Prosecution Issues
As above, the entire case thus turns on a single drafting choice: claiming “electric or electromagnetic signals” as alternatives, where the specification itself (not just the claims) repeats the same physically impossible embodiment. The panel noted that as both the claims and the written description recite transmitting electric signals over air, the court could not treat the claim language as an obvious drafting slip inconsistent with what the specification elsewhere made clear. If the specification had been clean, the patentee might have had a construction argument. It was not.
Satius tried to rescue the claim by arguing electric signals over air really meant the electric signal gets transformed into an electromagnetic signal inside the device, and it’s the electromagnetic signal that travels over the air. This argument essentially asked the court to read in a transformation step. The court declined, pointing to a different claim phrase a few lines later (“communicating the electric or electromagnetic signals to the air”) and invoking the presumption that different claim language means different things. Using “over” and “to” as near-synonyms in drafting, then arguing later that they must mean different things, is not a construction argument that tends to persuade a reviewing court.
The reexamination result is its own cautionary footnote: the PTO found independent claim 1 unpatentable but let dependent claims 11 and 18 stand (even though dependent claims cannot logically survive if their parent is invalid for reciting an impossibility baked into the core limitation of the independent claim). The enablement holding of the CAFC resolves this oddity by invalidating all three claims, but the reexamination split outcome is a reminder that reexamination and litigation can produce inconsistent snapshots of claim validity.
CAFC Decision and Reasoning
Indefiniteness — Reversed. While the CAFC agreed with the DC on claim construction, the court held that impossibility is not the same thing as indefiniteness. Citing Nautilus, the court explained that the definiteness inquiry asks whether the claims inform a skilled artisan, with reasonable certainty, about the scope of the invention rather than whether that scope is achievable. The court distinguished Synchronoss Technologies v. Dropbox, where claims requiring an impossibility were held indefinite, on the ground that those claims were nonsensical such that a skilled artisan would not understand them to reflect what the inventor regarded as the invention. Here, by contrast, both parties and the district court agreed on exactly what the impossible limitation meant as Samsung itself argued the claim “unmistakably claims” the impossibility. A claim can be clear about what it covers even when part of what it covers cannot exist. The court also flagged, in a footnote, that the DC reliance on expert testimony that the term would not have meaning to a skilled artisan was both conclusory and in tension with Samsung’s own argument that the term unmistakably meant something.
B. Enablement — Reached and Affirmed, Despite Not Being Decided Below. Rather than remand, the CAFC exercised its discretion to decide the enablement issue for the first time on appeal, applying the multi-factor test from Icon Health & Fitness and Singleton v. Wulff. The court found the issue fully briefed, legally straightforward, undisputed on the facts (nobody contests that transmitting electric signals over air is impossible), and certain enough in outcome that a remand would serve no purpose beyond generating the same conclusion on a second trip through the district court.
On the merits, the court applied Amgen v. Sanofi’s rule that a specification must enable the full scope of the claimed invention. Because claim 1 expressly covers an alternative embodiment that cannot be made or used by anyone, let alone a skilled artisan, the claims necessarily fail to enable their full scope. The court invoked the familiar formulation from EMI Group v. Cypress Semiconductor: an impossible limitation embodied within a claim renders the claim invalid. The court closed with Amgen’s reminder that “the more one claims, the more one must enable”; here, claiming an alternative that cannot be enabled by anyone was claiming more than the patent could support, falling, per the court” woefully short.”
Preparation and Prosecution Practice Takeaways
1) Audit alternative claim language for physical plausibility, not just grammatical correctness. “A or B” phrasing is a convenient drafting shorthand, but each alternative is independently examined for enablement and definiteness. If one branch of the “or” cannot exist, the claim does not get credit for the branch that can. Check both options before signing off, the same way you would any other limitation.
2) Make sure the specification’s own language does not undercut your construction arguments later. Here, the impossible phrase appeared in the written description, not just the claims thereby foreclosing any argument that the claim was a “scrivener’s error”. If a shorthand phrase is used loosely in the background section, consider whether it needs qualification before it migrates into claim language.
3) Do not rely on different claim terms meaning the same thing when convenient, then argue they’re different when it matters. Satius’s construction depended on treating “over air” and “to the air” as interchangeable at one point in the argument while needing them to carry different technical content at another.
4) Enablement and indefiniteness are different doctrines asking different questions; do not assume winning one wins the other. The claims here survived indefiniteness because they were clear about their scope, then lost on enablement because that scope included something physically unachievable. A claim can be perfectly easy to understand and still impossible to practice. Drafting counsel should deliberate both questions independently rather than merely thinking that because the claim is clear the limitations will automatically be enabled (life sciences practitioners already understand this point, but it is a rarer point that comes up for engineering practitioners).
This article is provided for general informational purposes and does not constitute legal advice.