It is well established that “a petitioner in an inter partes review … is not permitted to assert a ground of unpatentability under 35 U.S.C. § 112.” Dexcowin Golabl, Inc. v. Aribex, Inc., IPR2016-00436, Paper 12 (PTAB July 7, 2016). As such, IPR petitions solely relying on lack of written description under § 112 cannot avoid institution denial. A few IPR cases, however, teach an effective way for a petitioner to frame a § 112 dispute as a priority date dispute. Petitioners in those IPRs have successfully established the challenged patents were not entitled to an earlier filing date because they lacked written description support in the parent application under § 112. Interestingly, because the challenged patent and its parent application shared the same or substantially the same specification, the challenged patent itself also lacked written description support, making it unpatentable under § 112. But the Board allowed the IPRs to proceed because the petitioners simply did not seek invalidity under § 112. Their ultimate invalidity grounds were based on 35 U.S.C. § 102 or § 103, while the § 112 arguments were solely used to break the priority chain. The Board also consistently held that written description analysis for the purpose of determining priority date is distinguished from similar analysis for the purpose of invalidating a claim under § 112. This article explores IPR cases where petitioners effectively used § 112 to break the priority chain without getting their petitions denied.

In the recent case, Noco Co., Inc. v. Pilot, Inc., IPR2022-01417, Paper 12 (PTAB Feb. 6, 2024), the patent at issue (the ’236 Patent) claimed priority through multiple continuation applications. Noco at 11. Petitioner argued that the ’236 Patent was not entitled to an earlier filing date because the ’236 Patent specification or any other parent applications did not disclose “two different sensors with distinction purposes” in the claimed automobile charger. Id. at 11–12. Even though Petitioner’s reasoning was very similar to an argument that the patent was invalid for lack of written description under § 112, Petitioner carefully framed its argument as a priority date argument without explicitly raising unpatentability under § 112. The Board agreed with Petitioner, applying Petitioner’s priority date and eventually invalidating the ’236 Patent under § 102/103. Id. at 11–13, 40–41.

Similarly, in Motorola Mobility LLC v. Largan Precision Co., Ltd., IPR2022-01170, Paper 11 (PTAB Jan. 26, 2023), the challenged patent (the ’487 Patent) was a result of multiple continuation applications. Motorola at 5. The Board granted institution under § 102/103 based on the finding that the earliest parent application did not provide written description support for the challenged claims, and thus they “do not benefit from the priority date of the [earliest] application.” Id. at 20. Notably, the Board rejected Patent Owner’s argument that “Petitioner’s ‘challenge amounts to a backdoor way of asserting an impermissible challenge under 35 U.S.C. § 112 and the Board should deny institution on that basis.’” Id. at 10. The Board explained that “analyz[ing] whether the challenged claims have written description support from earlier applications … [is] not tantamount to finding claims unpatentable under 35 U.S.C. § 112.” Id. at 10–11 (emphasis added). Motorola also highlights another advantage for patent challengers in breaking the priority chain using § 112: asserting a published parent application as prior art. One of the invalidity grounds Petitioner asserted in this case was based on the earliest parent application of the ’487 Patent (“Chen359”). Id. at 16. Because (1) the ’487 Patent’s priority date was its own filing date (Mar. 23, 2017) due to the broken chain and (2) Chen359 was published on May 24, 2012, more than one year before the ’487 Patent’s priority date, Chen359 was qualified as prior art under § 102(b).

Finally, in SAP Am., Inc. v. Lakshmi Arunachalam, IPR2014-00414, Paper 24 (PTAB Aug. 17, 2015), three patents in the same family of the challenged patent (the ’894 Patent) were found invalid for lack of written description in a parallel lawsuit. SAP at 8. The ’894 Patent, which shared the substantially same specification as the other patents in the family suffered the same deficiency. Id. Against this backdrop, Petitioner, like cases above, used § 112 solely for the purpose of priority date challenge. Patent Owner responded that Petitioner exceeded the scope of IPR by “incorporating an improper analysis of compliance with written description requirements” under § 112. Id. at 20. In rejecting Patent Owner’s argument, the Board again confirmed that “[a] review of the disclosure for purposes of identifying the priority date for the claimed subject matter is appropriate and within the scope of inter partes review.” Id. at 21 (emphasis added). After determining the priority date as suggested by Petitioner, the Board found all the challenged claims unpatentable under § 103. Id. at 23.

Takeaway: IPR practitioners can strategically use § 112 to break the priority chain without directly asserting unpatentability under § 112. This approach, confirmed by recent IPR decisions, is an effective way to expand the potential pool of prior art, even including some patent owners' parent applications (as shown in Motorola). When a patent challenged in IPR claims the benefit of an earlier filing date, but lacks written description support, the petitioner should look out for the possibility of breaking the priority chain under § 112.

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