On July 22, 2025, the Court of Appeals for the Federal Circuit concluded that the Patent Trial and Appeal Board’s (the “PTAB”) decision not to apply interference estoppel and, therefore, to institute an inter partes review (“IPR”), was unreviewable and affirmed the PTAB’s final written decision finding that the challenged claims were invalid for obviousness.
IGT owns expired U.S. Patent No. 7,168,089 (the “’089 Patent”), entitled “Secured Virtual Network in a Gaming Environment.” The patent, which is broadly directed to the secure transfer of gaming software and communication of gaming information over public networks, was filed in 2002, and issued in January 2007.
In 2003, Zynga Inc. applied for a patent that contained claims that were copied from IGT’s earlier-filed ’089 Patent application after the ’089 Patent application had been published. The Board of Patent Appeals and Interferences of the Patent and Trademark Office (the predecessor to the PTAB) declared an interference proceeding in 2010. It then later authorized Zynga to move for judgment on the basis that the challenged claims of the ’089 Patent were invalid for obviousness, and it authorized IGT to move for judgement on the basis that Zynga lacked standing because the claims in its application were invalid for lack of written description under § 112. The Board of Patent Appeals and Interferences ultimately dismissed Zynga’s motion as moot when it found Zynga’s claims were not supported by written description. It explained that, without written description support in the specification, Zynga was not an appropriate party, and interference was not an appropriate forum; thus, the Board of Patent Appeals and Interferences terminated the interference.
In April 2021, IGT sued Zynga alleging infringement of the ’089 Patent. Later that same year, Zynga petitioned the U.S. Patent and Trademark Office to institute an IPR before the PTAB that challenged the ’089 Patent. In its petition, Zynga alleged obviousness based on a combination of prior art references different than it had alleged in its interference proceeding. IGT opposed the IPR, arguing that interference estoppel—a legal doctrine that prevents a party in a subsequent proceeding from raising arguments that could have been, but were not, presented in a prior interference proceeding—barred Zynga from raising its obviousness challenge.
The PTAB declined to apply interference estoppel and it instituted the IPR. The PTAB reasoned that (1) because the interference had been terminated on the “threshold issue” of lack of written description support, the Board of Patent Appeals and Interferences had never reached a conclusion on patentability over the prior art, and (2) it would not be fair to apply interference estoppel to Zynga, given that Zynga had provoked interference prior to the America Invents Act regulations and the consequences associated with those regulations (including the advent of IPRs). In the event that the estoppel regulation applied to IPRs, the PTAB waived application of the regulation per 37 C.F.R. § 42.5(b). On review, the Director of the USPTO similarly declined to apply interference estoppel.
During the IPR, the PTAB ultimately concluded that all challenged claims were unpatentable under § 103 for obviousness.
In its appeal to the Federal Circuit, IGT challenged the PTAB’s decision not to apply interference estoppel and challenged the PTAB’s conclusion on obviousness. Zynga responded that the decision not to apply interference estoppel was unreviewable and that the Board’s obviousness conclusion was correct.
In its decision, the Federal Circuit explained that Congress has explicitly protected the USPTO’s ability to decide whether or not to institute an IPR from judicial review in 35 U.S.C. § 314(d). Here, as IGT’s challenge was primarily related to whether the PTAB had the ability to institute an IPR, it was “within the general unreviewability principle.”
On the ultimate issue of obviousness, the Federal Circuit affirmed the PTAB’s decision.
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