Reichman Jorgensen Lehman & Feldberg Welcomes Top IP Trial and Appellate Lawyer Nathan Mammen as Partner

WASHINGTON, Dec. 16, 2025 /PRNewswire/ -- Reichman Jorgensen Lehman & Feldberg LLP (RJLF), a national trial boutique, has announced that intellectual property litigator and appellate lawyer Nathan Mammen has joined the firm as a partner in its Washington, D.C. office.

Mammen brings more than 20 years of experience and leads teams in complex, bet-the-company intellectual property matters. Notably, he played a pivotal role in the landmark Supreme Court case Amgen v. Sanofi, securing a decisive victory that clarified essential standards for patent enablement and set a far-reaching precedent in patent law. His practice spans diverse technologies, including medical devices, agricultural technology, wireless communications, and semiconductors. Mammen has represented clients at all levels, from trial courts and administrative boards to the U.S. Supreme Court, including extensive experience in the Federal Circuit and other courts of appeals.

"Nathan's ability to tackle high-stakes IP litigation with creativity and precision makes him a perfect fit for our firm," said Christine Lehman, Managing Partner of the firm's D.C. office. "His background at both the trial and appellate levels will help us continue delivering thoughtful, effective solutions for our clients."

A veteran of the U.S. Army, Mammen is deeply committed to pro bono service, particularly for his fellow veterans. He seeks to create systemic change through impact litigation, as highlighted by his recent work representing hundreds of senior Coast Guard veterans who were unlawfully forced into retirement, securing a significant outcome for the class.

"I joined RJLF to be part of a team of exceptionally talented lawyers who are not only committed to excellence but are also genuinely good people," shared Mammen. "The opportunity to deliver the best for clients in such a dynamic and collaborative environment is unparalleled—it doesn't get any better than this."

Mammen joins RJLF from Snell & Wilmer and previously spent over a decade as a partner at Kirkland & Ellis. Earlier in his career, he clerked for the Honorable Karen J. Williams of the U.S. Court of Appeals for the Fourth Circuit. He earned his J.D. with honors from The George Washington University Law School and a B.S. in Engineering from Purdue University.

About Reichman Jorgensen Lehman & Feldberg LLP

Reichman Jorgensen Lehman & Feldberg LLP (RJLF) is a national trial firm that handles high-stakes commercial, intellectual property, and white collar disputes. The firm is majority women-owned, reinventing the practice of law without the billable hour in favor of fee arrangements that align client interests. RJLF's attorneys are diverse, exceptionally credentialed, and passionate about trial advocacy. From offices in Silicon Valley, New York, Washington, D.C., Austin, and Atlanta, the firm tries cases and argues appeals throughout the country. Visit reichmanjorgensen.com to learn more.

Contact:
Jennifer Estremera
jestremera@reichmanjorgensen.com
(650) 623.1407

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