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.

For many years, the Office and Board had used a different indefiniteness standard, approved by the Federal Circuit in In re Packard, 751 F.3d 1307 (Fed. Cir. 2014) (per curiam). Under the Packard standard, a claim was indefinite “when it contains words or phrases whose meaning is unclear.” Id. at 1310, 1314.

In 2018, the Office changed the claim construction standard for post-grant trial proceedings. The standard, which had previously required the “broadest reasonable construction” of terms, was changed to align with the same claim construction standard used to construe claims in district courts, namely that claims should be construed pursuant to Philips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc). See Changes to the Claim Construction Standard for Interpreting Claims in Trial Proceedings Before the Patent Trial and Appeal Board, 83 Fed. Reg. 51340 (Oct. 11, 2018). Since that change, the Board has in some cases shown confusion as to whether to apply the Nautilus or Packard standard to questions of indefiniteness.

The Office’s memorandum clarifies that the Packard standard no longer applies in post-grant trial proceedings. Like the 2018 changes that changed the Board’s claim construction standard, the memorandum similarly changes the Board’s indefiniteness standard to align with that used in district courts. Applying the Nautilus standard for indefiniteness to post-grant trial proceedings will, in the words of the memorandum, “lead to greater uniformity and predictability, improve the integrity of the patent system, and help increase judicial efficiency.”