On January 6, 2021, former USPTO director Andrei Iancu issued binding guidance that aligned the approach of the Patent and Trial Appeal Board (PTAB) in analyzing indefiniteness in America Invents Act (AIA) post-grant proceedings with the approach used by federal district courts. Going forward, the PTAB is required to adhere to the approach set forth by the Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014).

Prior to the issuance of this guidance, the PTAB analyzed claims for indefiniteness under two differing approaches. In a first approach, certain PTAB panels followed the standard set forth in In re Packard, under which "[a] claim is indefinite when it contains words or phrases whose meaning is unclear." 751 F.3d 1307 (Fed. Cir. 2014) (per curiam). In a second approach, PTAB panels followed Nautilus, under which a claim of a patent challenged for indefiniteness is unpatentable for indefiniteness if the claim, when read in light of the patent specification and the prosecution history, fails to inform, with reasonable certainty, those skilled in the art about the scope of the invention." Nautilus, 572 U.S. at 901.

After the USPTO revised its rules in 2018 to change the claim construction standard used in post-grant proceedings from the broadest reasonable construction standard to the same standard used in district court, PTAB panels noted confusion as to whether Nautilus or Packard applies to questions of indefiniteness in AIA post-grant proceedings and parties continued to make arguments under either or both approaches.

Because indefiniteness questions are generally considered as part of the claim construction process, the guidance noted that the PTAB's approach to indefiniteness should likewise align with that used by district courts. And through this binding guidance, the USPTO clarified that Nautilus is the correct approach for analyzing indefiniteness under AIA post-grant proceedings.  

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