On January 6, 2021, the U.S. Patent & Trademark Office issued a memorandum to the Patent Trial and Appeal Board, requiring that, in post-grant trial proceedings, the Board must follow the same indefiniteness standard used in district courts. The Board must now analyze indefiniteness in post-grant trial proceedings under the standard set forth in Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014)—that is, a claim is indefinite if, read in light of the specification and the prosecution history, it fails to inform those skilled in the art about the scope of invention with reasonable certainty. Id. at 901.
