Nathan Lowenstein

Nathan Lowenstein is a founding and co-managing partner at Lowenstein & Weatherwax LLP, a Santa Monica-based patent litigation boutique. His practice is primarily focused on representing patent owners in high-stakes inter partes review (IPR) proceedings, patent reexaminations, Federal Circuit appeals, and related district court patent litigation. The firm is recognized for its specialized focus on patent owner-side post-grant proceedings.

Lowenstein's litigation experience spans a wide range of complex technologies, including semiconductors, computer hardware and software, telecommunications, medical devices, biotechnology, digital video, and electronic commerce. While the provided case data indicates all six of his tracked appearances are on the defendant side, this aligns with his firm's stated practice of exclusively representing patent owners in IPRs and other post-grant proceedings, where the patent owner is the defending party against challenges to their patent's validity.

He is particularly known for his extensive PTAB and IPR experience. Patexia ranked Nathan Lowenstein #1 in Patent Owner Performance among 5,650 PTAB practitioners nationwide for the July 2020–June 2025 period. The firm, under his leadership, has handled over 400 IPR/CBM proceedings and nearly 80 Federal Circuit appeals. Notable representations include obtaining 14 non-institutions of IPR petitions for Entropic Communications LLC against Comcast, Dish, and Cox, and securing non-institution for Security First Innovations LLC in an IPR brought by Google challenging a data security patent. He also served as lead counsel for VLSI Technology LLC, where he obtained non-institutions in 12 IPRs against Intel concerning patents involved in a $2.18 billion jury verdict, and successfully affirmed those victories at the Federal Circuit.

Lowenstein earned his B.A. with honors from the University of California, Santa Cruz (UCSC) and his J.D. from the University of California, Los Angeles (UCLA) School of Law in 2005. He was admitted to practice law in 2005 and is a member in good standing of the State Bar of California.