2025 Federal Circuit IP Appeals: Use of Applicant Admitted Prior Art (AAPA) in IPRs

“Applicant admitted prior art,” or AAPA, refers to when an applicant in a patent specification admits that certain subject matter is known in the prior art. The Federal Circuit decided cases in 2025 addressing the issue of how AAPA may be used as part of an obviousness argument in an inter partes review. Specifically, the Federal Circuit addressed whether and how IPR petitioners may use AAPA, along with prior art patents, in an unpatentability ground. 35 U.S.C. § 311(b) provides that a petitioner may raise a ground in an IPR only “under section 102 or 103 and only on the basis of prior art consisting of patents or printed publications.”

For example, Shockwave addressed an obviousness ground in an IPR petition that relied on a patent publication “as modified by AAPA” in combination with other prior art references. The Board found claims unpatent-able after “relying on AAPA only as evidence of the back-ground knowledge in the art.”

The Federal Circuit affirmed. The petitioner in Shockwave did not expressly state that AAPA formed the “basis” of its ground, but instead used AAPA only to show that certain technology was well known in the prior art. Petitioner argued that this general background knowledge was sufficient to meet claim limitations relating to that technology.

The Federal Circuit stated that its “case law has long recognized numerous permissible uses for general background knowledge in an IPR such as, ‘for example, furnishing a motivation to combine, or supplying a missing claim limitation.’” Applying that precedent, the court held that it is permissible for general knowledge, as evidenced in AAPA, to supply a missing claim limitation in a ground in an IPR petition. Here, the petitioner properly relied on general background knowledge to supply missing claim limitations (which the patent owner did not argue were novel to the invention) and used AAPA as evidence to establish that general background knowledge.

Interestingly, two weeks later, on July 31, 2025, the then-Acting U.S. Patent and Trademark Office (USPTO) Director issued a guidance memorandum on AAPA that superseded prior USPTO memoranda on the issue. The July 2025 memo states that AAPA, expert testimony, common sense, and other evidence “that is not ‘prior art consisting of patents or printed publications’ (collectively, ‘general knowledge’)” may not be used to supply a missing claim limitation. This statement appears to diverge from Federal Circuit decisions, including Shockwave, holding that general background knowledge, as evidenced by AAPA, for example, can supply a missing claim limitation.

The July 2025 memo further states that, going forward, the USPTO will not “waive” the requirements of 37 C.F.R. § 42.104(b)(4), which provides that an IPR petition “must specify where each element of the claim is found in the prior art patents or printed publications relied upon.” The memo cites Shockwave in a footnote and states that “[w]hile Rule 104(b)(4), as applied in some cases, may be narrower than 35 U.S.C. § 311(b), enforcing Rule 104(b)(4) is the best course of action to provide certainty to the parties, the Board, and the public, and to allow for the efficient administration of the Office.” The memo does, however, note that “general knowledge,” which presumably includes that established by AAPA, may still be used in an IPR to support a motivation to combine or to demonstrate the knowledge of a skilled artisan.

This article appeared in the 2025 Federal Circuit IP Appeals: Summaries of Key 2025 Decisions report.