USA Trends and Developments Contributed by: Matthew D Powers, Samantha Jameson, Azra Hadzimehmedovic and Aaron Nathan, Tensegrity Law Group LLP
Tensegrity Law Group 555 Twin Dolphin Drive Suite 650 Redwood Shores, CA 94065 USA Tel: +1 650 802 6000 Fax: +1 650 802 6001 Email: matt@tensegritylawgroup.com Web: tensegritylawgroup.com
Patent Litigation Trends in the Life Sciences in the USA This chapter focuses on three recent trends that affect life science and pharmaceutical litigation. First, in just the past year, multiple decisions have addressed the written description requirement for pharmaceutical and life science patents, reinforcing the fact-specific nature of the inquiry and providing a view into deci ‑ sional trends in life science and pharmaceutical cases. Second, significant changes in the procedures for instituting Inter Partes Review (IPR) proceedings in the United States Patent and Trademark Office (the “Pat ‑ ent Office”) have occurred. While procedural changes earlier in the year appear to have had a smaller effect on life science and pharmaceutical patent IPR insti ‑ tution rates, the full effect of more recent changes remains to be seen. Third, the Patent Office recently changed its approach to inventorship for inventions created with the assistance of AI. With AI becoming an increasingly common feature of research and devel ‑ opment efforts, this issue has become increasingly important. The Patent Office’s change likely avoids the rejection of claims for insufficient human contributions and defers the issue for later litigation. Written Description Written description drove the outcome of multiple cases in 2025. In high-profile cases, claims were found invalid for insufficient written description, which confirms that the written description requirement has been and likely will continue to be a key focal point in life science and pharmaceutical cases. But there were also cases last year in which the written description requirement was met. These cases reinforce that the written description analysis continues to be fact-spe ‑
cific and focused on the disclosures in the specifica ‑ tion, the testimony regarding what one of ordinary skill would have understood, and the precise scope of the claims. Recent decisions reinforce the need for both defendants and plaintiffs to develop persuasive fac ‑ tual evidence and present properly framed arguments to succeed on written description issues. Last year, plaintiffs who failed to marshal persuasive evidence saw their claims invalidated for inadequate written description on appeal, despite having the presump ‑ tion of validity and favourable jury verdicts. The core requirement for a sufficient written description under Section 112 (a) is that a patent “reasonably conveys to those skilled in the art that the inventor had pos ‑ session of the claimed subject matter as of the filing date.” Ariad Pharms., Inc. v Eli Lilly & Co. , 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc). The test for writ ‑ ten description “requires an objective inquiry into the four corners of the specification from the perspective of a person of ordinary skill in the art.” Id. Whether there is adequate written description is a question of fact and varies based on the context. Id. At the end of 2025, the Duke and Seagen cases reinforced the importance of the written description requirement to patents that disclose a broad genus defined by a chemical structure and claim a narrower subgenus. Duke Univ. v Sandoz Inc. , No 2024-1078, 2025 LX 578815, at *8 (Fed. Cir. 18 November 2025) (undisputed that the disclosed genus included “bil ‑ lions of compounds” and the claims covered fewer than 5,000); Seagen Inc. v Daiichi Sankyo Co., Ltd. , Nos 2023-2424, 2024-1176, 2025 LX 511083, at *15 (Fed. Cir. 2 December 2025) (noting that the disclosed genus included “over 47 million species” while the
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