CAFC Partially Affirms PTAB Unpatentability Decision for Samsung but Vacates on Unchallenged Claims

The U.S. Court of Appeals for the Federal Circuit (CAFC) on Wednesday affirmed in part a decision of the Patent Trial and Appeal Board (PTAB) finding certain claims of ST Case1Tech, LLC’s (ST1’s) patent obvious, but vacated the decision as to two claims that petitioner Samsung had not challenged before the Board. The panel included Judges Reyna, Taranto and Stark and was authored by Judge Stark.

U.S. Patent No. 9,491,542 is titled “Automatic Sound Pass-Through Method and System for Earphones” and was challenged by Samsung via inter partes review (IPR) after ST1 sued Samsung for infringement. Samsung argued that claims 1-10 and 13- 20 of the patent were invalid due to obviousness based on three prior art references: Rosenberg, Ichimura and Visser. The PTAB ultimately found all of the challenged claims obvious over combinations of the prior art, but also found unchallenged claims 11 and 12 unpatentable without explanation.

On appeal, the CAFC agreed with the Board’s construction of the claim term “detecting a cessation of the voice activity,” known as the “cessation limitation.” ST1 argued the cessation limitation should be construed to mean detecting an end of speech,” which excludes “momentary pauses within speech,” while Samsung argued it should be construed broadly enough “to also encompass detecting the end of a word within a sentence or conversation.” The CAFC found both the claim language and specification supported the Board’s construction. The court further rejected ST1’s argument that a construction so broad would undermine the purpose of the invention, finding that another claim limitation addressed that concern. Since the construction was the only challenge raised by ST1 on appeal with respect to claims 1-6 and 13-18, the CAFC affirmed the unpatentability determinations on those claims.

Turning to claims 7-9, ST1 said the PTAB’s finding that there was a motivation to combine prior art references Rosenberg and Visser lacked substantial evidence. But the CAFC rejected this argument, noting that the disclosure in the prior art references plus Samsung’s expert opinion sufficed to support the Board’s findings.

With respect to claims 11 and 12, however, the CAFC  vacated the Board’s determination that they had been found unpatentable by a preponderance of the evidence. “The parties agree that claims 11 and 12 were not challenged in Samsung’s petition,” wrote the CAFC, and “the Board may not invalidate patent claims on grounds it identifies sua sponte that are not actually raised by the petitioner,” as set forth in Corephotonics, Ltd. v. Apple Inc., 84 F.4th 990, 1011 (Fed. Cir. 2023).

In a separate decision on Wednesday issued by the same panel, the CAFC also affirmed another PTAB decision finding claims of ST1’s U.S. Patent No. 9,270,244 invalid as obvious based on the Board’s construction of a claim term.