In a memo to the Administrative Patent Judges of the Patent Trial and Appeal Board (PTAB) yesterday, the USPTO declared that indefiniteness in AIA post-grant proceedings would follow the standard set forth in Nautilus, Inc. v. Biosig Instruments, Inc.:

“... a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.”

The Nautilus standard, which district courts apply in patent litigation, differs from the standard for ex parte examination (including appeals to the PTAB) as well as for reexamination and reissue, which instead defines a claim as indefinite if “it contains words or phrases whose meaning is unclear.” This standard, set forth in In re Packard, has long been the standard during examination. Initially, it also served as the standard for covered business method review, post-grant review, and inter partes review proceedings (collectively, AIA post-grant proceedings).

Then, in 2018, the USPTO announced a change in claim construction standards for AIA post-grant proceedings, leaving the “broadest reasonable interpretation” standard used during examination in favor of the arguably-narrower standard used in infringement litigation. This newfound alignment with district court standards left the PTAB unsure whether to apply the standards of Nautilus or of Packer for indefiniteness in AIA post-grant proceedings. By issuing their January 6, 2021 memo, the PTAB has resolved the question, allowing judges and parties alike to address indefiniteness issues with greater certainty.