Matthew Guarnieri
202.888.1741 | 2001 K Street, NW, Suite 850 North, Washington, DC 20006
Matt Guarnieri is a principal at Gupta Wessler LLP, where he focuses on Supreme Court, appellate, and complex litigation. Matt has nearly 15 years of experience in briefing and arguing high-stakes appeals, with particular expertise in administrative and constitutional law.
Before joining Gupta Wessler, Matt served as an Assistant to the Solicitor General, where he represented the United States before the Supreme Court. In that role, Matt personally argued 13 cases in the Supreme Court—winning 10 of them in whole or part—and authored more than 100 briefs at the certiorari and merits stages.
Matt led the government’s briefing in numerous high-profile Supreme Court cases, including the Biden Administration’s efforts to defend the authority of federal regulators in Loper Bright Enterprises v. Raimondo and Sackett v. EPA. Matt was also centrally involved in defending federal public health measures during the COVID-19 pandemic—for example, vaccination requirements at federally funded healthcare facilities serving vulnerable patients—and he argued (and won) Yellen v. Confederated Tribes of the Chehalis Reservation, which preserved the Treasury Department’s award of more than $500 million in relief funds for Alaska Native tribes.
Matt is especially proud of the work he did in the Solicitor General’s Office that overlapped with Gupta Wessler’s core mission of advocating for justice on behalf of employees, consumers, investors, and other plaintiffs. In one of his first arguments, Matt represented the federal government in support of a class of ERISA beneficiaries represented by Gupta Wessler. The government and the firm’s client prevailed 9-0 in that case, Intel Corp. Investment Policy Committee v. Sulyma. Matt also advocated the winning position on behalf of the government in cases involving, among other things, the False Claims Act, employee healthcare benefits, intellectual property, and the rules of evidence.
Matt’s arrival at Gupta Wessler marks a historic moment: the first time an attorney has transitioned from the Solicitor General’s Office directly into an appellate practice devoted exclusively to representing plaintiffs and the public interest. He brings to the firm a deep working knowledge of how to position cases for success on appeal—whether that means preserving a hard-won judgment, overturning an adverse result, or strategizing about further review. In joining Gupta Wessler, Matt adds to the firm’s roster of experienced Supreme Court advocates and cements its reputation as the nation’s leading plaintiff-side appellate boutique.
Earlier in his career, Matt worked as an Attorney-Adviser in the Department of Justice’s Office of Legal Counsel. He was responsible in that role for providing internal legal advice to the Executive Branch about a wide range of questions of federal law, including the separation of powers. Matt was awarded the Attorney General’s Distinguished Service Award for his contributions.
Matt was also previously an associate at WilmerHale LLP in Washington, D.C., where he cut his teeth briefing a wide range of complex legal issues at all levels of the judiciary. Among other highlights, Matt played a central role in drafting winning Supreme Court briefs on behalf of a class of WARN Act plaintiffs (Czyzewski v. Jevic Holding Corp.) and a veteran-owned small business (Kingdomware Technologies, Inc. v. United States). He also represented the respondent in Gelboim v. Bank of America, which established the rules for appealing pretrial dismissal of individual claims in an MDL. Matt joined WilmerHale after clerking for Judge Michael Boudin of the U.S. Court of Appeals for the First Circuit and Judge Louis H. Pollak of the U.S. District Court for the Eastern District of Pennsylvania.
Matt received his J.D. from Columbia Law School. He was a James Kent Scholar in each of his three years, an editor of the Columbia Law Review, and a finalist in the Harlan Fiske Stone Moot Court competition. Matt received his A.B. in Social Studies, magna cum laude, from Harvard College, where he was elected to Phi Beta Kappa. He was born and raised in Baltimore and remains an Orioles fan, for better or worse. Mostly worse.
