Mark Harris is head of the White Collar Defense & Investigations Group and co-head of the Appellate Group. Mark is also a former federal prosecutor and law clerk at the U.S. Supreme Court. An experienced white-collar criminal defense lawyer, he represents companies and individuals in their most complex and difficult litigation matters. Mark’s appellate cases span the gamut from intellectual property and labor relations to constitutional law and administrative law. Since 2017, Mark has represented the Financial Oversight and Management Board for Puerto Rico—the entity created by Congress to oversee Puerto Rico’s bankruptcy, the largest in American history—in dozens of appeals before the U.S. Court of Appeals for the First Circuit. In May 2023, he prevailed before the Supreme Court in an 8-1 decision that recognized the Board’s immunity from suit. He is a Fellow of the American Academy of Appellate Lawyers and a past American Lawyer Litigator of the Week.