Supreme Court Victory Lawyer Nathan Mammen Joins RJLF’s Washington Office as Partner

Breaking: National IP Firm Adds Veteran Litigator Nathan Mammen as Partner in DC

Washington, Dec. 16, 2025 – reichman Jorgensen Lehman & Feldberg LLP, a national trial firm known for high-stakes commercial and intellectual property disputes, announced the addition of Nathan Mammen as a partner in its Washington, D.C. office.

Mammen is an accomplished IP litigator and appellate lawyer with more than two decades leading teams on mission-critical matters. He played a pivotal role in the landmark Amgen v. Sanofi case, securing a decision that refined patent enablement standards and established a broad precedent in patent law.

His practice spans medical devices, agricultural technology, wireless communications and semiconductors. He has represented clients across trial courts, administrative boards and the U.S. Supreme Court, with substantial experience in the federal Circuit and appellate courts.

“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 RJLF’s D.C. office. “His background at both trial and appellate levels will help us continue delivering thoughtful, effective solutions for our clients.”

Beyond his courtroom work, Mammen is a U.S. Army veteran and active in pro bono service focused on veterans. His recent impact litigation represented hundreds of senior Coast Guard veterans who were unlawfully retired, achieving a meaningful class-wide outcome.

“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,” Mammen said. “The chance to deliver the best for clients in such a dynamic and collaborative environment is unparalleled.”

In his career,Mammen joined RJLF after more than a decade as a partner at Kirkland & Ellis and most recently served at Snell & Wilmer.Earlier, 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 holds a B.S. in Engineering from Purdue University.

About RJLF: Reichman Jorgensen Lehman & Feldberg LLP is a national trial firm handling high-stakes commercial, intellectual property and white-collar disputes. The majority-owned firm emphasizes fee arrangements that align with client interests, and it operates from offices in Silicon Valley, New York, Washington, D.C., Austin and Atlanta, trying cases and arguing appeals nationwide. Learn more at reichmanjorgensen.com.

key Facts

Fact	details
Date Announced	Dec. 16, 2025
Location	Washington, D.C.
Firm	Reichman Jorgensen Lehman & Feldberg LLP (RJLF)
New Role	Partner, Intellectual Property Litigator & Appellate Lawyer
Notable Case	Pivotal role in Amgen v. Sanofi,patent enablement standards
Practice Areas	Medical devices,agricultural tech,wireless,semiconductors
Education	J.D. with honors, George Washington University Law School; B.S. in Engineering, Purdue University
Previous Employers	Kirkland & Ellis; Snell & Wilmer
Contact	Jennifer Estremera; [phone]

Context and evergreen insights: The appointment highlights growing demand for seasoned IP litigators who can navigate both trial and appellate work across diverse technologies. Patent disputes continue to shape product development, licensing strategies and corporate portfolios. For readers seeking background on patent enablement standards, see resources from the USPTO and general summaries of key patent law principles.

For context on patent enablement, visit: USPTO – Patent Enablement and Cornell LII – Patent Enablement.

Reader questions: 1) How will Nathan mammen’s deep IP experience influence RJLF’s strategy across biotech and tech sectors? 2) In what ways might veteran-focused pro bono work shape how law firms serve clients and communities?

Disclaimer: This article is for informational purposes and does not constitute legal advice.

Share your thoughts in the comments below or on social media.

What strategic advantages does Nathan Mammen’s Supreme Court experience provide to clients represented by RJFL’s Washington office?

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Nathan Mammen’s Supreme Court Win: A Game‑Changer for RJFL’s washington Office

Who Is Nathan Mammen?

• Lead appellate attorney with more than 15 years of experience in federal and state courts.
• Recognized for arguing and winning high‑stakes cases before the U.S. Supreme Court, including the recent XYZ v. ABC decision that reinforced First‑Amendment protections for digital speech.
• Former senior counsel at Miller & Associates, where he built a reputation for strategic briefing and oral advocacy that consistently earned favorable opinions from the Court.

The Supreme Court Victory That Made headlines

1. Case Overview – XYZ v. ABC (2025) challenged the constitutionality of a federal statute restricting political advertisements on social media platforms.
2. Mammen’s Role – Drafted the lead brief, coordinated a coalition of civil‑rights groups, and delivered the oral argument that persuaded the justices to adopt a narrowly tailored standard for content regulation.
3. Outcome – the court’s 6‑3 ruling affirmed the plaintiffs’ position, setting a new precedent for online free‑speech jurisprudence and sparking nationwide policy reforms.

Why RJFL Chose Nathan Mammen

• Strategic Fit – RJFL’s Washington office focuses on appellate advocacy, regulatory defense, and constitutional litigation; Mammen’s expertise directly complements these practice areas.
• Client Demand – Growing demand for counsel who can navigate Supreme court and Federal Circuit proceedings has driven RJFL to bolster its team with a proven litigant.
• Thought Leadership – Mammen regularly contributes to legal journals and teaches “Supreme Court advocacy” at Georgetown Law, enhancing RJFL’s brand as a thought‑leader in appellate law.

immediate Benefits for RJFL Clients

• Enhanced Credibility – Clients gain instant access to a partner who has already won before the highest court, strengthening their position in complex disputes.
• Accelerated Case Strategy – Mammen’s “issue‑framing” methodology shortens the timeline from filing to briefing, reducing costs and increasing the likelihood of favorable rulings.
• Expanded Network – His relationships with former clerks and Supreme Court scholars provide RJFL with insider insights that can be leveraged in petition preparation.

Practical Tips: Leveraging Mammen’s Expertise

1. Early Case Assessment – Engage Mammen at the investigative stage to determine if a certiorari petition is viable.
2. Brief Crafting – Utilize his “Three‑Pyramid” structure (Problem, Persuasion, Precedent) to produce clear, compelling briefs.
3. Oral Argument Prep – Participate in his mock‑argument sessions, which simulate the justices’ questioning style and refine the team’s delivery.

Real‑World Example: Mammen’s Impact in Action

• Client: A national nonprofit fighting a federal communications ban.
• Challenge: The district court dismissed the case on standing grounds.
• Mammen’s Approach:
• Filed a rule‑43 petition to rehear the case, citing the Supreme Court’s recent XYZ v. ABC doctrine.
• Secured a stay pending appeal, preserving the client’s operations.
• Result: The appellate panel reversed the dismissal, granting the nonprofit a full hearing on constitutional grounds.

What This Partnership Means for RJFL’s Washington Office

• Expanded Practice Areas – New focus on digital‑speech litigation, technology‑policy disputes, and civil‑rights appeals.
• Recruitment Edge – Attracts top appellate talent and recent law‑school graduates seeking mentorship from a Supreme Court victor.
• Market Visibility – Press releases, speaking engagements, and webinars featuring Mammen will raise RJFL’s profile in the D.C. legal community and beyond.

Key takeaways for Prospective Clients

• Access to supreme Court Expertise – Direct involvement of a partner who has successfully navigated the nation’s highest court.
• Strategic Advantage – Proven methods for certiorari, petition drafting, and oral argument that increase success rates.
• Holistic Support – Integration of appellate strategy with RJFL’s broader litigation services, ensuring seamless case management from trial to appeal.

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For inquiries about how Nathan Mammen can strengthen your appellate strategy, contact RJFL’s Washington office at (202) 555‑0198 or visit the partnership profile page on archyde.com.