On February 4, 2020, the Federal Circuit issued a precedential decision in Samsung Electronics America, Inc. v. Prisua Engineering Corp.. The decision remanded an inter partes review (IPR) proceeding to the Patent Trial and Appeal Board (PTAB) for review of claims under the proposed novelty and obviousness grounds, despite the fact that the Board had determined the claims to be indefinite.
As part of the America Invents Act in 2012, congress created the IPR proceedings at the PTAB. With this new procedure, petitioners were granted the opportunity to challenge the validity of patents in a more efficient and fast-paced manner. However, IPR’s are limited to institution on grounds for rejection under §102 for anticipation and §103 for obviousness. This notably excludes challenges under §112 for indefiniteness.
In the PTAB proceeding leading to appeal, Samsung had petitioned for review of Claims 1-4, 8, and 11 of U.S. Pat. No. 8,650,591. In the PTAB’s Final Written Decision, the Board invalidated claim 11 for obviousness, but declined to analyze 1-4 and 8. Their reasoning was that the claims were mixed subject matter under IPXL analysis, making the claims indefinite and precluding the Board from continuing the review since indefiniteness extends beyond the congressionally granted scope for IPRs.
On appeal, the Federal Circuit explained that the mere fact that the claims were indefinite does not bar the PTAB from reviewing them under 102 and 103:
Even though the validity of the challenged claims may be subject to question for IPXL-type indefiniteness, that is simply another ground on which the claims might be challenged in an appropriate forum (other than the Board)… It does not necessarily preclude the Board from addressing the patentability of the claims on section 102 and 103 grounds. In the remand proceedings, the Board should determine whether claim 1 and its dependent claims are unpatentable as anticipated or obvious based on the instituted grounds.
With the decision, the Federal Circuit preserves the ability for petitioners to use IPRs to challenge patents more efficiently, even in the case where the claims are indefinite.
 IPXL Holdings, LLC v. Amazon.com, Inc., 430 F.3d 1377, 1384 (Fed. Cir. 2005)
 Samsung Electronics America v. Prisua Engineering Corp., Case No. 19-1169, Document 52 at 20 (Fed. Cir. 2020).