Addressing the issues of claim construction and the requisite expert qualifications to testify on obviousness and anticipation, the US Court of Appeals for the Federal Circuit vacated a Patent Trial & Appeal Board decision invalidating half of the challenged patent’s claims and instructed the Board to clarify whether the patent owner’s expert was indeed qualified as a person of ordinary skill in the art (POSITA). Sierra Wireless, ULC v. Sisvel S.P.A., Case Nos. 23-1059; -1085; -1089; -1125 (Fed. Cir. Mar. 10, 2025) (Moore, CJ:  Schall, Taranto, JJ.)

Sisvel owns a patent directed to methods for retrieving data lost during wireless transmission. The prior art taught methods for flagging lost protocol data units (PDUs) so that the data transmitter could retry the transmission. Sisvel’s patent includes a timer that prescribes a period of time to elapse before alerting a transmitter of a missing PDU, allowing the transmission to be completed without notification. The patent has 10 claims, two of which are independent. The primary independent claim has four limitations, including one related to stopping the timer before a status report issues if the missing PDU is located and another related to issuing a status report upon the timer’s expiration. The limitations are linked by the word “and.”

Sierra Wireless initiated inter partes review (IPR), arguing that all 10 of the claims were both anticipated and obvious in light of the “Sachs” prior art patent. The Board found that half of the claims, including both independent claims, were anticipated and obvious. In finding that the other claims were not unpatentable, the Board relied on the testimony of Sisvel’s expert. Both parties appealed.

Sisvel raised two arguments in support of the claims the Board found unpatentable. First, Sisvel argued that the Board misconstrued the two above-noted limitations as mutually exclusive. Sisvel argued that the prior art had to teach both limitations to invalidate the claim. Second, Sisvel argued that the Board’s interpretation of Sachs’ teachings to include the first of the two limitations was unsupported by substantial evidence.

The Federal Circuit agreed. On the claim construction issue, the Court found that the two limitations in issue could not be mutually exclusive because the claim language linked them using the word “and.” To construe the limitations as mutually exclusive would be inconsistent with the unambiguous claim language. With regard to the prior art, the Court looked to Sachs Figure 5, which the Board relied upon in determining that the prior patent had taught the first limitation. Both the figure and the patent’s surrounding language made clear that the time referenced therein was dependent upon reordering of PDUs, not upon receiving missing ones. The Court thus vacated the Board’s invalidity determination as not supported by substantial evidence.

In its appeal, Sierra argued that the Board’s reliance on Sisvel’s expert’s testimony to find certain claims not unpatentable was an abuse of discretion. The Federal Circuit agreed, finding that the Board abused its discretion by not finding that the proposed expert qualified as a POSITA before relying upon his testimony. The Court found that the proposed expert’s qualifications fell outside the parameters the Board itself set when defining who qualified as POSITA. The Court noted that while the proposed expert had more work experience than the Board required, he lacked the requisite electrical engineering degree. The Court further noted that his work experience was not identical to the adopted level of skill in the art. Because obviousness and anticipation are both viewed from the perspective of one of ordinary skill in the art, it was improper for the Board to rely on the proposed expert’s testimony. The Court thus vacated the Board’s decision and remanded with instructions that the Board determine whether the proposed expert qualified as a POSITA.