Mark D. Harris practices in the areas of appeals and white-collar criminal defense. He is co-head of the Appellate Practice Group at Proskauer, which was honored in 2011 by Law360 as one of five Appellate Practices of the Year in the U.S., and by the National Law Journal with a spot on its annual "Appellate Hot List." Mark has been recognized as a "Star" in the field of Appellate Litigation by the Benchmark Litigation Guide. He also has an active criminal defense practice, representing institutional and individual clients in government investigations and prosecutions.

Mark has handled dozens of matters in the U.S. Supreme Court and other appellate courts in a variety of areas spanning criminal law, sentencing, copyright, labor relations, administrative law, and personal injury.

From 1997 to 2002, Mark served as an Assistant U.S. Attorney for the Southern District of New York, during which he prosecuted a broad spectrum of federal crimes, including health care fraud, financial fraud and corporate embezzlement. He tried a number of jury trials and argued before the U.S. Court of Appeals for the Second Circuit. Previously, he was a clerk to Justices John Paul Stevens and Lewis F. Powell, Jr., at the U.S. Supreme Court, and Judge Joel M. Flaum at the U.S. Court of Appeals for the Seventh Circuit.

Since 1996, Mark has been a member of the Board of Editors of the Federal Sentencing Reporter and a frequent contributor. His work on behalf of non-U.S. clients was featured in the American Lawyer's Litigation 2006 supplement. He has lectured on both criminal law and appellate practice before the International Bar Association, the ABA Section of Litigation, the ABA Section of Criminal Law, and the ABA Section of Employment and Labor Law, and has been interviewed by Bloomberg Radio, the National Law Journal, WINS AM-1010, Law360, Legal Times, and other news organizations.