Leonard is Special Counsel for National Security in the Department of Justice's (DOJ) Computer Crime and Intellectual Property Section (CCIPS) and Head of CCIPS' Cybersecurity Unit. He joined DOJ's Terrorism and Violent Crime Section in 1991. In the late 1990's, he served as Special Counsel and Special Investigative Counsel to DOJ's Inspector General and supervised sensitive investigations of Department officials and programs. In 2000, he joined CCIPS where he has prosecuted computer crime and intellectual property cases; advised on matters related to searching and seizing electronic evidence and conducting electronic surveillance; and chaired the Organization of American States' Group of Government Experts on Cybercrime. Leonard has taught courses on cybersecurity and cybercrime at Georgetown Law School and Columbus School of Law in Washington, D.C.