J. Gregory (Greg) Deis is a former federal prosecutor whose practice focuses on complex commercial litigation, internal investigations and white-collar criminal defense. Greg is an experienced trial lawyer, having tried over a dozen criminal and civil cases to verdict, most as first chair. He has also served as lead counsel in numerous criminal and civil appeals.
At the firm, Greg has conducted internal investigations on behalf of a variety of clients. Greg also regularly represents companies and senior executives in criminal and regulatory investigations, including investigations involving the FCPA, health care, tax, money laundering and environmental offenses. Greg's complex commercial litigation experience involves various areas of law, including the False Claims Act, RICO, tax controversy, federal securities law, shareholder derivative claims, trademark law and defamation.
Prior to rejoining Mayer Brown, Greg served as an Assistant US Attorney in Chicago, assigned to the Public Corruption section. Greg prosecuted numerous public officials and law enforcement officers with fraud, bribery, extortion and tax offenses, including the bribery prosecution of an Illinois state representative. His trial experience includes the month-long trial of William Cellini, a long-standing political insider in Illinois convicted of extorting campaign contributions for then Governor Rod Blagojevich. In addition to his corruption experience, Greg investigated and prosecuted a wide range of federal criminal cases involving complex financial fraud, procurement fraud, money laundering, computer offenses and international drug trafficking.
Greg joined the US Attorney's Office after working at the firm from 2003-07. He has been an adjunct professor of criminal procedure and trial advocacy at DePaul University College of Law. Greg began his legal career as a law clerk for the Honorable Deanell Reece Tacha, Chief Judge of the US Court of Appeals for the Tenth Circuit.