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Explore the latest in patent, trademark, and copyright cases on the Merchant & Gould LLP blog. Stay informed with expert insights on intellectual property law updates.

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Last week, the U.S. Court of Appeals for the Federal Circuit issued a precedential opinion in <a href="https://www.cafc.uscourts.gov/opinions-orders/23-2262.OPINION.7-22-2025_2547840.pdf"><em>IGT v. Zynga Inc.</em>, No. 2023-2262 (July 22, 2025)</a>, affirming the Patent Trial and Appeal Board’s determination that every challenged claim of IGT’s U.S. Patent No. 7,168,089 is unpatentable as obvious.

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IGT filed a patent application in 2002 addressed to methods for casino gaming machines to securely communicate with other devices over the internet, which issued as U.S. Patent No. 7,168,089. Later, Zynga filed an application that copied several of the ’089 patent’s claims, triggering an interference at the Board of Patent Appeals and Interferences (which is the predecessor of the Patent Trial and Appeal Board and both of which are hereafter referred to as the “Board”). Zynga moved for judgment that the ’089 Patent’s claims were invalid as obvious, but the Board never reached that claim. Instead, it terminated the interference because the claims of Zynga’s application lacked written-description support.

A decade later, IGT sued Zynga for infringing the ’089 Patent. Zynga petitioned for inter partes review (IPR) on obviousness grounds. IGT argued interference estoppel barred Zynga from making its obviousness challenge. The Board disagreed and instituted review, finding interference estoppel did not apply because (1) the Board never reached the obviousness inquiry during the interference, and (2) the interference proceeding occurred before the America Invents Act, which established the guidelines for interference estoppel. The Director agreed. After review on the merits, the Board concluded that all challenged claims were unpatentable as obvious. IGT appealed.

The Federal Circuit affirmed. The Court reasoned that review of the Board’s decision not to apply interference estoppel falls within the general rule that institution decisions are unreviewable. The Court further held that to the extent review of the decision were allowed, the Board did not err in declining to apply interference estoppel in this case. In particular, the Court explained common-law claim preclusion principles support the finding that Zynga is not precluded from challenging the ’089 Patent’s claims on obviousness grounds because the Board never reached the obviousness inquiry in the interference proceeding. The Court also rejected IGT’s procedural and substantive challenges to the Board’s final written decision of unpatentability.

CAFC Affirms Refusal to Apply Interference Estoppel

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