On March 10, 2025, the United States Court of Appeals for the Federal Circuit issued a decision in Sierra Wireless, ULC v. Sisvel S.P.A., vacating and remanding a ruling from the Patent Trial and Appeal Board (PTAB) regarding U.S. Patent No. 7,869,396. The case presents significant discussions on patent infringement, anticipation, obviousness, and expert witness qualifications in intellectual property law. Here, we break down the major legal issues addressed by the court.

Background of the Case

The dispute centers on a wireless communication technology patent owned by Sisvel S.P.A., which covers a method to improve data transmission reliability using a modified automatic repeat request (ARQ) technique. Sierra Wireless, Honeywell International Inc., and Telit Cinterion Deutschland GmbH (collectively, the Appellants) challenged the patent’s validity through inter partes review (IPR), arguing that the claims were anticipated by and obvious in view of a prior patent application known as Sachs.

The PTAB found that some claims of the ’396 patent were unpatentable, while others were upheld as valid. The Federal Circuit’s review focused on two key aspects: (1) whether PTAB properly analyzed the anticipation and obviousness challenges, and (2) whether PTAB appropriately relied on testimony from Sisvel’s expert witness.

Key Legal Issues

1. Anticipation and Obviousness Analysis

Sisvel appealed PTAB’s finding that certain claims (1, 2, and 6–8) were unpatentable due to anticipation and obviousness based on Sachs. The Federal Circuit ruled that PTAB erred in its claim construction and factual findings, particularly regarding:

• Claim Interpretation: The court rejected PTAB’s interpretation that limitations 1[c] and 1[d] of the patent were mutually exclusive. It emphasized that both conditions must be satisfied under the plain language of the claim, contradicting PTAB’s reasoning.
• Substantial Evidence Standard: The court found that PTAB’s conclusion—that Sachs disclosed a key limitation of the patent—was unsupported by substantial evidence. Specifically, the prior art reference described stopping a timer after reordering data packets, whereas the ’396 patent required stopping the timer upon receiving a missing packet. This misinterpretation led the court to vacate PTAB’s ruling of anticipation and obviousness.

2. Expert Witness Qualification

Sierra Wireless contested PTAB’s reliance on testimony from Sisvel’s expert, Regis Bates, arguing that he was not qualified as a person of ordinary skill in the art (POSITA). The court agreed, emphasizing:

• Standard for Expert Testimony: A witness testifying about anticipation and obviousness must possess at least the ordinary skill in the field of the patent at issue. PTAB had defined an ordinarily skilled artisan as someone with a degree in electrical engineering or a similar field and relevant industry experience in wireless communication.
• Lack of Qualification: Bates lacked the technical degree required by PTAB’s definition and did not demonstrate specific experience in designing wireless data transmission methods. Because PTAB failed to justify its reliance on Bates’ testimony, the court found this reliance to be an abuse of discretion and vacated PTAB’s ruling on this basis.

Implications for Patent Law

This ruling reinforces several important principles in patent law:

• Claim Construction Precision: The Federal Circuit continues to emphasize that patent claims must be interpreted according to their plain language. The decision serves as a reminder that claim elements must be carefully analyzed, particularly when evaluating anticipation and obviousness.
• Substantial Evidence Requirement: PTAB decisions must be backed by solid evidence, particularly when determining whether prior art disclosures align with a challenged patent.
• Expert Witness Standards: Courts are becoming more stringent about expert witness qualifications, ensuring that testimony reflects the perspective of an ordinarily skilled artisan. This decision may lead to closer scrutiny of expert qualifications in future IPR proceedings.

Conclusion

The Federal Circuit’s decision in Sierra Wireless v. Sisvel is a notable victory for patent owners seeking robust claim protection and a cautionary ruling for parties challenging patents through IPR. By vacating PTAB’s findings on claim construction, anticipation, and expert witness credibility, the court underscores the importance of proper evidentiary standards in patent litigation. Moving forward, both patent holders and challengers should carefully consider these legal principles when arguing for or against patent validity in IPR proceedings.

With the case now remanded for further proceedings, it remains to be seen whether PTAB will reassess its findings or whether new expert testimony will shape the final outcome. Regardless, this ruling sets a strong precedent for how courts interpret patent claims and evaluate expert testimony in intellectual property disputes.

By Charles Gideon Korrell