In July 2025, the Federal Circuit delivered a pivotal decision in Shockwave Medical, Inc. v. Cardiovascular Systems, Inc., addressing the role of applicant admitted prior art (AAPA) in inter partes review (IPR) proceedings. This ruling has significant implications for patent litigation and the strategic considerations of legal professionals in the field.
Shockwave Medical holds U.S. Patent No. 8,956,371, which pertains to an angioplasty catheter system employing intravascular lithotripsy (IVL) to treat atherosclerosis. Cardiovascular Systems, Inc. (CSI) challenged all 17 claims of this patent through an IPR petition. The Patent Trial and Appeal Board (PTAB) found claims 1–4 and 6–17 unpatentable as obvious but upheld the validity of claim 5. Both parties appealed these determinations.
A central issue in the appeal was the PTAB’s use of AAPA. The Federal Circuit clarified that while AAPA cannot serve as the primary basis for an IPR petition, it is permissible as evidence of general background knowledge to demonstrate that certain claim limitations were known in the art. The court emphasized that the grounds raised in the petition are determinative, noting that CSI’s petition did not present AAPA as the foundation for its obviousness arguments. Consequently, the PTAB’s reliance on AAPA to establish background knowledge was deemed appropriate.
Regarding claim 5, the Federal Circuit reversed the PTAB’s decision, concluding that the claim was unpatentable. The court found that the PTAB had erred by not considering the combined teachings of the prior art references, which collectively rendered claim 5 obvious. This reversal underscores the necessity for a comprehensive analysis of prior art combinations in assessing patent validity.
In response to this decision, the United States Patent and Trademark Office (USPTO) issued a memorandum refining the use of AAPA in IPR petitions. The memorandum specifies that AAPA may be utilized for background information and to demonstrate a motivation to combine references but cannot be employed to supply a missing claim limitation absent in the prior art patents and printed publications cited by the petitioner. This directive aims to provide clarity and reduce litigation over the use of AAPA in IPR proceedings.
For legal professionals, this development highlights the importance of precise petition drafting and a thorough understanding of the permissible scope of prior art in IPRs. The Federal Circuit’s decision and the subsequent USPTO guidance serve as critical references for navigating the complexities of patent challenges and ensuring compliance with established standards.