Argument Shifting At The PTAB: Balancing The Right Of Reply Against The Petition's Role As Case-In-Chief

• Published date: 04 April 2024
• Subject Matter: Intellectual Property, Patent
• Law Firm: Mayer Brown
• Author: Mr Joseph Mahoney and Cecilia G. Rambarat

A vexing issue in post-grant patent practice is understanding the limits of how far a patent challenger can deviate from the four corners of its petition during the proceeding. The petition is the challenger's case-in-chief. Petitions cannot be amended to address either the patent owner's claim construction positions or its arguments and evidence rebutting the petitioner's grounds of unpatentability. Of course, the petitioner can respond to the patent owner's arguments, but it "may not submit new evidence or argument in reply that it could have presented earlier [in the petition], e.g., to make out a prima facie case of unpatentability." US Patent Trial and Appeal Board, Consolidated Trial Practice Guide 73 (Nov. 2019). See also Rembrandt Diagnostics, LP v. Alere, Inc., 76 F.4th 1376, 1384 (Fed. Cir. 2023) ("the very nature of the reply and sur-reply briefs are to respond (whether to refute, rebut, explain, discredit, and so on) . . . within the confines of 37 C.F.R. ' 42.23(b)."). But what are those confines, and what facts and issues are fairly framed by the petition?

The answers are necessarily fact-dependent, but the Federal Circuit and the US Patent Trial and Appeal Board ("PTAB") have established certain boundaries for a number of scenarios. In the leading cases of Rembrandt and Axonics, Inc. v. Medtronic, Inc., 75 F.4th 1374 (Fed. Cir. 2023), the court permitted the consideration of the petitioners' "new" arguments and evidence, and explained that a petitioner is permitted to: (1) expand on previously raised arguments that have a nexus to an argument made by the patent owner or the Board; and (2) assert the same "legal ground" as its petition by relying on the "same prior art" to support the "same legal argument," even where a new example or an additional portion of the same prior art reference is used by the petitioner in reply. Rembrandt, 76 F.4th at 1383-84; Axonics, 75 F.4th at 1384 (petitioner can reply to patent owner's new claim construction by relying on the same prior art from the petition).

Conversely, a reply is improper where a petitioner: (1) introduces a new prior art reference that was not disclosed in the petition to support a contention that is "meaningfully distinct" from what is disclosed in the petition; or (2) introduces a new theory of unpatentability, such as where the petitioner asserted in its petition that a single reference disclosed a limitation and then instead argued in its reply that there was a motivation to combine...