Brian Matsui is a partner in Morrison Foerster’s Appellate and Supreme Court practice. Brian is a go-to appellate advocate for sophisticated clients in complex appeals.
Brian has a nationwide appellate practice. He has argued cases in federal and state appellate courts throughout the country, winning appeals involving commercial disputes, securities litigation and enforcement, government contracts, consumer class actions, and intellectual property. He has led appeals in the D.C., Second, Fourth, Fifth, Ninth, Eleventh, and Federal Circuits. His arguments include significant victories in class action appeals and in appeals for leading financial services companies, with multiple victories in the Ninth Circuit, where he clerked. Brian has recently gone six for seven when representing appellants, including a precedential victory in the Ninth Circuit in a licensing dispute concerning alleged patent misuse. He also argued and won a D.C. Circuit appeal against the Securities and Exchange Commission (SEC) about the retroactivity of part of the Dodd-Frank Act. As a result of Brian’s win, the SEC had to change its enforcement practices against certain securities industry professionals.
Clients frequently turn to Brian for his substantial experience with appeals in the Federal Circuit, praising him as “an invaluable advocate in patent matters” (Chambers USA). Brian has won 14 of his last 16 appeals in that Court. His arguments before the Federal Circuit include winning appeals from district courts, the Patent Trial and Appeal Board, and the International Trade Commission. He has handled appeals in a myriad of industries, including mobile devices, pharmaceuticals, medical devices, semiconductors, and software.
Brian also plays a key role on trial teams, advising clients on both critical legal issues and appellate preservation. He recently argued and prevailed against a summary judgment invalidity motion in a case involving Chugai Pharmaceutical Co. Ltd.’s revolutionary antibody recycling technology, which ultimately led to a $775 million settlement on the eve of trial for Chugai.
A former law clerk for the United States Supreme Court, Brian has authored many briefs in that Court, including on important constitutional and statutory interpretation issues. He often represents clients’ interests in amicus briefs in significant Supreme Court cases affecting the business community.
Leading publications have recognized Brian for his appellate skills. Chambers USA ranks him in its Intellectual Property: Appellate category, The Legal 500 US recommends him for Appellate Litigation, and the National Law Journal named him one of its Minority 40 Under 40.
Brian also dedicates significant time to pro bono matters. He argued and won two significant appeals—in the Second and Ninth Circuits—obtaining reversals of judgments that had denied private rights of action under the Child Welfare Act in precedential decisions. Brian also led the Morrison Foerster team who co-counseled a successful Eighth Amendment challenge to Florida’s imposition of a life without the possibility of parole sentence to a juvenile offender convicted of a non-homicide crime.
Brian serves on the board of directors of the Lawyers’ Committee for Civil Rights Under Law. For years, Brian chaired the ABA’s seven-person Standing Committee for Amicus Curiae Briefs. He served on the American Intellectual Property Law Association’s amicus committee and co-chaired the National Asian Pacific American Bar Association’s amicus committee. Brian also served as an appellate lawyer representative for the Ninth Circuit.
Before entering private practice, Brian clerked on the United States Supreme Court for Justice Anthony M. Kennedy. He also clerked for Judge Pamela Ann Rymer in the Ninth Circuit and Judge David F. Levi in the Eastern District of California.
While in law school, Brian served as managing editor of Volume 51 of the Stanford Law Review and was elected to the Order of the Coif.
Ranked in Intellectual Property: Appellate
Chambers USA 2025
Named Life Sciences Star in Patent Litigation
Legal Media Group
Recommended for Dispute Resolution: Appellate
The Legal 500 US 2022-2025
Named an “IP Star”
Recommended in the areas of Supreme Court and Appellate Litigation and Patent Litigation
Named a “Minority 40 under 40”