USPTO To Limit Use of General Knowledge in IPRs: What Practitioners Need to Know

On July 31, 2025, the United States Patent and Trademark Office (USPTO) issued a significant memorandum signaling a shift in inter partes review (IPR) strategy, namely, the Office will no longer waive the enforcement of 37 C.F.R. § 42.104(b)(4). Effective for all IPR petitions filed on or after September 1, 2025, this rule requires that petitions must “specify where each element of the claim is found in the prior art patents or printed publications relied upon.”

This change means that petitioners can no longer rely on general knowledge, including expert testimony, common sense, or applicant admitted prior art (AAPA), to supply a missing claim limitation. These sources may still be used to support a motivation to combine or demonstrate the understanding of a person of ordinary skill in the art, but they can no longer be a substitute for disclosures in patents or printed publications when mapping claim elements.

This memorandum reverses a prior policy under the USPTO’s 2020 and 2022 guidance, which allowed limited reliance on general knowledge in combination with printed publications. The decision aligns with recent Federal Circuit case law, Qualcomm Inc. v. Apple Inc., 24 F.4th 1367 (Fed. Cir. 2022) and 134 F.4th 1355 (Fed. Cir. 2025), which limited the use of AAPA as the "basis" of an IPR ground.

This policy change imposes a significantly higher burden on petitioners. Going forward, petitioners must ensure that every element of each challenged claim is explicitly identified in one or more prior art patents or printed publications. Any failure to meet this requirement will render the petition deficient under 35 U.S.C. § 312(a)(4), subjecting it to denial at the institution stage.

As a result, the selection and presentation of prior art references becomes even more critical. Petitioners can no longer rely on general knowledge or expert declarations to "fill in the gaps" for limitations not clearly disclosed in the cited references. Art must be selected and applied with the understanding that it must, on its face, disclose each element of the challenged claims.

For patent owners, this development strengthens procedural defenses. They will now be able to argue, at the threshold, that a petition fails on its face where it attempts to rely on general knowledge, applicant statements, or expert opinion to supply missing limitations. This could lead to more early-stage denials and reduce the likelihood of institution for weaker challenges.

While the new approach arguably imposes a stricter procedural hurdle than 35 U.S.C. § 311(b) itself, the USPTO believes that strict enforcement of Rule 42.104(b)(4) will improve certainty, notice, and procedural integrity across IPR proceedings.

For IPR petitions filed on or after September 1, 2025, general knowledge cannot be used to supply missing claim elements. Petitioners should reassess their art strategies now to ensure full compliance. Likewise, patent owners should be prepared to challenge noncompliant petitions early in the process.

https://www.uspto.gov/sites/default/files/documents/aapa_memo_final__signed.pdf

If you have questions about how this policy shift may affect a pending or planned IPR, our team is available to assist.

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