Implicit, LLC owned two patents, the '791 and '252 patents, which originally listed Edward Balassanian and Scott Bradley as the only co-inventors. Sonos, Inc. petitioned for inter partes review of these patents, arguing they were unpatentable based on prior art. The Patent Trial and Appeal Board issued final written decisions in September 2019, holding the challenged claims unpatentable. Implicit appealed, and the case was remanded following the Supreme Court's decision in Arthrex, Inc. v. Smith & Nephew, Inc., to allow for Director review, which was denied. In December 2021, after the final decisions were issued, Implicit requested a certificate of correction to add Guy Carpenter as an inventor. The certificate was issued in August 2022. Implicit then argued that this correction retroactively validated its earlier antedating argument, claiming Carpenter's work predated the prior art. The Board, however, determined that Implicit had forfeited this argument by failing to raise it during the initial proceedings.
The Federal Circuit addressed whether the retroactive effect of 35 U.S.C. § 256, which allows for the correction of inventorship, prevents the application of equitable forfeiture doctrines. The court held that forfeiture can apply notwithstanding the retroactive nature of a § 256 correction. The court reasoned that while the PTO granted the correction, the Board properly determined that Implicit forfeited the right to rely on the new inventorship to challenge the final written decision. The court found that Implicit had the evidence of Carpenter's involvement and the opportunity to seek correction and assert the theory earlier in the proceeding. Unlike the precedent in Egenera, Inc. v. Cisco Sys., Inc., where a judicial change in claim construction necessitated a re-evaluation of inventorship, no such change occurred here. Implicit had possession of the evidence from the start and intentionally presented a different inventorship theory initially. The court noted that allowing Implicit to raise this argument now would constitute sandbagging, where a party permits a proceeding to continue on a certain course and then claims error if the outcome is unfavorable. Because the Board did not abuse its discretion in finding forfeiture, the court affirmed the decision without reaching the arguments regarding judicial estoppel or waiver.
This decision reinforces the finality of inter partes review proceedings. Patent owners cannot use certificates of correction issued after a final written decision to revive arguments they failed to raise in a timely manner. It establishes that diligence is required when seeking corrections to inventorship, particularly when the change could directly affect the outcome of a pending or recently concluded proceeding. The ruling limits the ability of patent owners to strategically delay asserting inventorship changes until after an unfavorable decision, ensuring that the IPR process remains efficient and predictable.
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