Biography
Mark regularly serves as lead outside appellate counsel to major global companies in their most significant matters. His significant appeals have included most areas of business litigation, including securities, intellectual property, employment, and competition law. He has exceptional experience briefing and arguing cases in the Supreme Court of the United States – including winning landmark decisions in Lucia v. SEC, Alice Corp. v. CLS Bank, and Janus Capital Group v. First Derivative Traders – and the federal courts of appeals. Mark also regularly represents clients in federal district courts, frequently serving as litigation strategist in class actions and other complex commercial cases.*
Mark is extremely well regarded by leading legal industry publications. He is ranked as one of the top practitioners nationally for Appellate Law by Chambers USA, where commentators have called him a "master strategist and a brilliant writer" who “pushes hard on the strong points in terms of his briefs and oral advocacy” and “has a great courtroom presence.” Mark is also recognized by Legal 500 as a top-ranked national “Leading Lawyer” for both Appellate: Courts of Appeal and Appellate: Supreme Courts. He has been named a National “Litigation Star” for both Appellate and General Commercial by Benchmark Litigation, which also has awarded him “Appellate Lawyer of the Year” honors. Additionally, Mark has been recognized by Best Lawyers in America® in the fields of Appellate Practice and Securities / Capital Markets Law, by Super Lawyers in the Appellate category, by LMG Life Sciences for General Patent Litigation, and by IAM Patent – which called him “undoubtedly one of the top appellate specialists in the country” – for his work in the Federal Circuit. He also has been selected by Law360 on numerous occasions as a national “MVP,” including in the Antitrust and Securities categories, named a “Litigator of the Week” by The American Lawyer, and selected by Lawdragon 500 to its 2025 “Leading Litigators in America” list.
Before joining Weil, Mark was a partner at another international law firm, where he served as Co-Chair of its nationwide Appellate and Constitutional Law Practice Group. Earlier, he served as a law clerk to Justice Sandra Day O’Connor of the Supreme Court of the United States, and to Judge Alex Kozinski of the United States Court of Appeals for the Ninth Circuit. Mark also worked as what is now called a Bristow Fellow in the Office of the Solicitor General of the United States.
He earned his law degree with high honors from the University of Chicago Law School, where he served as Executive Editor of the Law Review. Mark’s undergraduate degree was conferred by the University of California at Berkeley.
*includes matters handled prior to joining Weil