The USPTO Issues Guidance on How Prior-Art Admissions in a Challenged Patent’s Specification Can Be Used in an IPR

August 24, 2020
Firm Publication

On August 18, 2020, the U.S. Patent and Trade Office (USPTO) issued a Memorandum clarifying that admissions about prior art in a patent challenged in an inter partes review (IPR) cannot serve as the sole basis for a ground of rejection, but may be used in the following instances:

  1. To supply missing claim elements.
  2. To support a motivation to combine references.
  3. To show the general knowledge of the skilled artisan.

The Memorandum addressed what role a challenged patent’s specification can play under 35 U.S.C. § 311(b)’s limitation that IPR challenges may only be based on “prior art consisting of patents or printed publications.”  Previously, some Board decisions held that prior-art admissions “are not prior-art patents that alone may serve as the basis for an IPR,” while others permitted the use of “admissions only in conjunction with other prior art patents and printed publications.”

The Memorandum explained that, under § 311(b), “any patent that is used as the ‘basis of’ a request for inter partes review must be a prior art patent, not the challenged patent.”  However, admissions in a challenged patent may be used “when they evidence the general knowledge possessed by someone of ordinary skill in the art.”  “That evidence, if used in conjunction with one or more prior art patents or printed publications forming ‘the basis’ of the proceeding under § 311, can support an obviousness argument.”

Citing the recent decision in Koninklijke Philips v. Google, 948 F.3d 1330 (Fed. Cir. 2020), the Memorandum noted that the Federal Circuit rejected the argument that, because “‘general knowledge’ is not a ‘patent[] or printed publication,'” it cannot be used to supply missing claim elements in an IPR.  Nevertheless, assertions of general knowledge must be supported by evidence.

The Memorandum then listed the following permissible uses of general knowledge under § 103:

  1. Supplying missing claim limitations that were generally known in the art prior to the invention (for pre-AIA patents) or the effective filing date of the claimed invention (for post-AIA patents).
  2. Supporting a motivation to combine particular disclosures.
  3. Demonstrating the knowledge of the ordinarily-skilled artisan at the time of the invention (for pre-AIA patents) or the effective filing date of the claimed invention (for post-AIA patents) for any other purpose related to patentability.

The Memorandum noted that parties may also dispute the “significance or meaning of statements in the specification or other evidence” and Patent Owners may dispute whether the Petitioner has properly characterized statements in the specification.  The Board shall adjudicate such disputes “as they arise,” given that they will be highly fact-dependent.


This Memorandum clarifies how the Board will apply admissions contained within the challenged patent itself.  Although admissions alone may not form the sole basis for a ground of rejection, they may be used to bolster invalidity arguments.  For example, Petitioners may be able to fill in gaps in their arguments by using admissions to supply missing claim elements.  Patent Owners, on the other hand, must be prepared to explain away any such admissions.

If you have questions about what these cases mean for your business, please contact the authors.