PTAB Cannot Invalidate Challenged Claims for Indefiniteness in an IPR

18 February 2020 PTAB Trial Insights Blog
Authors: Melissa J. El Menaouar

The Federal Circuit definitively rejected arguments to cancel challenged claims for reasons other than anticipation or obviousness in an inter partes review proceeding.1  In Samsung Electronics America, Inc., v. Prisua Engineering Corp.,2 the Federal Circuit rejected Samsung’s challenge that the PTAB has authority to cancel claims it has found indefinite in an IPR.  

After being sued for infringing U.S. Patent 8,650,591 (assigned to Prisua), Samsung filed an IPR petition3 challenging claims 1-4, 8, and 11 of the ’591 patent.The Board initially instituted the IPR only on the ground challenging claim 11 as obvious over a published U.S. patent application.  The Board explained it did not institute on any ground challenging claims 1-4 and 8, because it could not determine the scope of those claims, which were indefinite under 35 U.S.C. § 112, paragraph 2 in accordance with the analysis set forth in IPXL5  and 35 U.S.C. § 112, paragraph 6.While the IPR was pending, the Supreme Court decided SAS,7 and the Board subsequently modified its institution decision to include all challenged claims on all grounds presented in the petition presented in the petition.  The Board allowed the parties to file supplemental briefs and evidence on the newly added claims and grounds.  

In supplemental briefing, Samsung argued the Board should cancel claims 1-4 and 8 for indefiniteness or, in the alternative, the Board should apply the prior art to the claims despite the indefiniteness issue.  In its final written decision, the Board held claim 11 unpatentable for being obvious in view of a published U.S. patent application, repeating its conclusion that claims 1-4 and 8 were indefinite and declining to apply the prior art to anticipation or obviousness.  Samsung and Prisua cross-appealed the decision.

On appeal, Samsung argued the Board should have canceled claims 1-4 and 8 for indefiniteness or, in the alternative, if the Board did not have the authority to cancel the claims for indefiniteness, then they should have reviewed the claims for anticipation and obviousness.  Samsung argued that even though the statutemay not authorize the Board to institute an IPR based on a claim’s indefiniteness, after institution has been established on a statutorily authorized ground, the Board has the authority to cancel claims on indefiniteness grounds.  Samsung pointed to several provisions in the IPR statute in an effort to show Congress authorized the Board to cancel claims for indefiniteness after an IPR has been instituted, including an interpretation of the term “patentability” in the IPR statute.

Although the court acknowledged that “it is undisputed that the Board may review newly added claims for compliance with section 112,”10,11  the court unambiguously rejected “Samsung’s contention that the IPR statute authorizes the Board to cancel challenged claims for indefiniteness.”12  In reaching its conclusion, the court reviewed the history of challenging the validity of patent claims both in the federal courts and at the USPTO, including an explanation of the types of challenges available under each (e.g., patentable subject matter, anticipation, obviousness, and indefiniteness).  Additionally, the court explained “the proper course for the Board to follow, if it cannot ascertain the scope of a claim with reasonable certainty for purposes of assessing patentability, is to decline to institute the IPR or, if the indefiniteness issue affects only certain claims, to conclude that it could not reach a decision on the merits with respect to whether petitioner had established the unpatentability of those claims under sections 102 or 103.”13

In response to Samsung’s alternative argument, the court agreed that the Board improperly construed claim 1 as a “means-plus-function” claim and prematurely ended its anticipation and obviousness analysis.  The court explained that even if claims 1-4 and 8 may be subject to question for IPXL-type indefiniteness, the Board should have further considered the anticipation and obviousness grounds.  The court noted its “decision here is limited to IPXL-type indefiniteness and does not affect claims that are indefinite for other reasons,” and “does not affect the disposition of cases in forums that are authorized to consider indefiniteness as a basis for invalidating a claim.”14  The court additionally upheld the Board’s determination that claim 11 was unpatentable as obvious.

In summary, the court concluded “[i]t would not be proper for the Board to cancel claims on a ground that is unavailable in an IPR”15 and even if claims are subject to question for indefiniteness, this “does not necessarily preclude the Board from addressing the patentability of the claims on section 102 and 103 grounds.”   The Samsung decision cautions petitioners to thoroughly evaluate the scope of each challenged claim and all potential grounds of invalidity in assessing the proper forum to bring an invalidity challenge to a patent’s claims.


135 U.S.C. § 311.
2Samsung Electronics America, Inc., v. Prisua Engineering Corp., No. 2019-1169 (Fed. Cir. 2020).
3IPR No. IPR2017-01188.
4Claims 1 and 11 are independent and claims 2-4 and 8 ultimately depend on claim 1.
5IPXL Holdings, LLC v., Inc., 430 F.3d 1377, 1384 (Fed. Cir. 2005) held that a single claim covering both an apparatus and a method of use of that apparatus is indefinite under section 112, paragraph 2.
635 U.S.C. § 112, paragraph 6 provides the requirements for “means-plus-function” limitations in a claim.
7SAS Institute, Inc. v. Iancu, 138 S. Ct. 1348 (2018).
835 U.S.C. § 311.
935 U.S.C. § 318(a).
1035 U.S.C. § 316(d).
11Samsung Electronics America, Inc., v. Prisua Engineering Corp., No. 2019-1169, slip op. at p. 12 (Fed. Cir. 2020).
12Id., p. 11.
13Id., p. 16.
14Id., p. 21, n. 5.
16Id., p. 20.

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