USA Guide 2026 : California
Provided by Lowenstein & Weatherwax LLP
Lowenstein & Weatherwax LLP is a nationally recognized patent litigation boutique focused on representing patent owners in high-stakes PTAB proceedings, patent reexaminations, related Federal Circuit appeals, and district court patent litigation. The firm is particularly known for patent owner-side inter partes review defense, post-grant strategy, institution-stage advocacy, expert-driven technical analysis, its written and oral advocacy, and appellate work arising from complex patent validity disputes.
L&W has litigated more than 400+ IPR/CBM proceedings and nearly 80 CAFC appeals, often against many of the country’s largest law firms and technology companies. Its matters span semiconductors, computer hardware and software, telecommunications, medical devices, biotechnology, digital video, electronic commerce, and other technically complex fields.
The firm’s PTAB work has been repeatedly recognized by Patexia. Patexia ranked founding partner Nathan Lowenstein #1 in Patent Owner Performance among 5,650 PTAB practitioners nationwide for the July 2020–June 2025 period. Patexia also identified Lowenstein & Weatherwax as the top-performing IPR firm in the country for 2013–2018, and as the sixth most active and sixth best-performing firm representing patent owners for 2020–2025. The firm combines boutique efficiency with deep PTAB, appellate, and trial-court experience, giving patent owners a focused litigation team built for technically demanding, high-value patent disputes.
Provided by Chambers
Lowenstein & Weatherwax LLP is a highly regarded litigation boutique recognized for its expert handling of inter partes reviews for a wide array of clients. It counts a wide array of technology sector names among its client base, as well as telecommunications.
Co-founders Nathan Lowenstein and Kenneth Weatherwax are key contacts at the firm.
Provided by Chambers
Lowenstein & Weatherwax LLP represented Neural AI LLC in four IPR petitions brought by NVIDIA.
Provided by Chambers
Lowenstein & Weatherwax are able to handle work in any technology sector. They work efficiently and have meticulous strategy and written work product. They are experts on PTAB procedure and have encyclopedic knowledge, maximizing efficiency for their clients.
We have always been delighted with their service and value to our business. They have always adapted flexibly and successfully.
They have more experience and have been very successful in the field of patent law and the inter partes review procedures.
L&W are very accomplished litigators, particularly when handling IPRs. They are able to navigate highly technical areas while also excelling in the legal and advocacy portions of an IPR. They use a structured process that ensures all filings are dealt with in a timely manner and eliminates time based pressure.
The lawyers at Lowenstein & Weatherwax exhibit deep technical understanding for the patents involved in their matters. They are highly strategic when it comes to the policies and procedures of the USPTO, particularly as the relate to high-value patents.
USA: Spotlight 2026
Practice area: Intellectual Property
Location: Los Angeles
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