Since its inception, the PTAB has gained a negative reputation among patent owners, even being referred to as “patent death squads.”[1] However, in the past year the Federal Circuit has provided a glimmer of hope for patent owners through the expansion of inter partes review (IPR) estoppel. Because of Cal. Inst. of Tech. v. Broadcom Ltd., 25 F.4th 976 (U.S. Fed. Cir. 2022) and the more recent case Click-to-Call Techs. LP v. Ingenio, Inc., 45 F.4th 1363 (Fed. Cir. 2022), a patent which survives an initial IPR petition now has greater protection in later validity challenges.

Generally, section 35 U.S.C. § 315(e)(2) estops parties from relitigating invalidity arguments in civil proceedings which were previously raised during an IPR. In recent years, the scope of 35 U.S.C. § 315(e)(2) was in flux after Shaw Indus. Grp. v. Automated Creel Sys., 817 F.3d 1293 (Fed. Cir. 2016). The Shaw court emphasized that § 315(e) applies to grounds “during that inter partes review.” Id. at 1300; 35 U.S.C.S. § 315(e). A first portion of district courts held estoppel applies to arguments that could have been raised in the petition.[2] While other district courts, in comparison, applied IPR estoppel only to arguments that could have been raised during the actual IPR proceeding.[3]

Earlier this year, the Federal Circuit clarified the scope of IPR estoppel in Cal. Inst. of Tech. v. Broadcom Ltd., 25 F.4th 976 (U.S. Fed. Cir. 2022). Before beginning litigation, Apple filed multiple IPR petitions challenging the validity of claims related to data encoding. Id. at 982. The PTAB held Apple failed to show the claims were unpatentable as obvious. Id. at 983. Afterward, Apple asserted, in district court, a new obvious validity challenge using prior art not previously asserted during the IPR proceedings. Id.  Ultimately, the district court held the defendants were estopped under 35 U.S.C § 315(e)(2) as they could have raised the claims in the IPR petitions. Id.

While reviewing the case, the Federal Circuit took the opportunity to overrule Shaw and clear up the dispute in the lower courts. Cal. Inst. of Tech., 25 F.4th 976, 991 (U.S. Fed. Cir. 2022). The Federal Circuit held “estoppel applies not just to claims and grounds asserted in the petition and instituted for consideration by the Board, but to all grounds not stated in the petition but which reasonably could have been asserted against the claims included in the petition.” Id. Since it was undisputed that the defendants were aware of all prior art of the time of filing the IPR petition, the Federal Circuit affirmed the district court. Id.

As mentioned above, the Federal Circuit continued this trend in Click-to-Call Techs. LP v. Ingenio, Inc., 45 F.4th 1363 (Fed. Cir. 2022). Here, the PTAB Board partially instituted an IPR petition in 2013 for patent challenger Ingenio. See id. at 1366. However, after partial review was granted, the Supreme Court held the PTAB must address every patent challenge in an IPR petition. See SAS Inst., Inc. v. Iancu, 138 S. Ct. 1348, 1354 (2018). As such, Ingenio had an opportunity to seek remand at the PTAB, but instead proceeded in district court. Click-to-Call Techs. LP v. Ingenio, Inc., 45 F.4th 1363, 1365 (Fed. Cir. 2022). The Federal Circuit held Ingenio was estopped by the partial institution because they did not seek remand at the PTAB. See id. at 1366.

The expansion of IPR estoppel is potentially a win for patent holders. If the claims can survive the first IPR petition, the patent holder is in a much greater negotiating position. Before any future challenges, the challenging party must first prove they could not have reasonably raised the argument during the IPR. Though the trend of expanding IPR estoppel may be halted in the next few months as Apple has since filed a writ of certiorari seeking to overturn the Cal. Inst. of Tech decision.

[1]Peter Pitts, Patent Death Squads’ vs. Innovation, WALL ST. J. (June 10, 2015, 7:23 PM),

[2]See, e.g., Biscotti Inc. v. Microsoft Corp., No. 213CV01015JRGRSP, 2017 WL 2526231, at *7 (E.D. Tex. May 11, 2017).

[3]See, e.g., Verinata Health, Inc. v. Ariosa Diagnostics, Inc., Case No. 12-cv-5501, 2017 WL 235048, at *3 (N.D. Cal. Jan 19, 2017).