Charles was formerly a partner at Dickie, McCamey & Chilcote. Prior to that, he served as an Assistant District Attorney in Allegheny County for more than seven years, Assistant U.S. Attorney for the Western District of Pennsylvania for more than six years, and as Assistant Chief of the Environmental Crimes Section of the U.S. Department of Justice in Washington, D.C., for more than nine years.

During his tenure with the Justice Department in Washington, D.C., Charles served as lead counsel for the United States in the criminal prosecution of U.S. v. Exxon and Exxon Shipping Co. for the massive 1989 Exxon Valdez Alaska oil spill. The criminal and civil settlements obtained by the government represented at the time the largest comprehensive settlement in the history of law enforcement. Charles has also prosecuted major environmental cases in Pittsburgh, Miami, Anchorage, San Juan and Washington, D.C.

While an Assistant U.S. Attorney, Charles was in the Narcotics and Organized Crimes Section and served as Chief of the Special Prosecutions and White Collar Crime Sections. He served as lead counsel for the United States Attorney’s Office in Pittsburgh in the 1988 Ashland Oil spill, where the company was fined $2.25 million after a tank collapse sent 700,000 gallons of diesel fuel into the Monongahela and Ohio Rivers.

Charles has made more than 50 professional presentations to government employees, the environmental regulated community and attorneys. He is the co-author of an article on corporate officer responsibility printed in the Environmental Law Reporter. In addition, he has been quoted in The Wall Street Journal, The New York Times and other national media.

Charles has served on faculties and made presentations and submitted papers to the American Bar Association, ALI-ABA, the Pacific Admiralty Conference, the Practicing Law Institute, the Allegheny Bar Association and the Pennsylvania Bar Institute. He was profiled by the Environmental Law Institute in the Environmental Forum in March/April 1999 regarding his work on the Exxon Valdez litigation and his current practice. In addition, he was referred to by the Environmental Law Institute as “a father of parental liability” in corporate litigation matters.

He also served as moderator of the Corporate Legal Times Roundtable on the topic, “Corporations are Striving to do the Right Thing,” published in November 1999. He was on the faculty of the ABA 23rd Annual National Institute on White Collar Crime in San Francisco, CA, in March 2009. In September 2009, he made a presentation to the Los Angeles County Bar Association, International Law Section, on the Foreign Corrupt Practices Act.

Additionally, Charles was cited by name in the U.S. Department of Justice’s Public Lands and National Treasures publication celebrating the centennial anniversary of the Environmental and Natural Resources Division of the Justice Department, and featured as one of the agency’s top cases of the past 100 years – the Exxon Valdez oil spill, the largest environmental settlement in the nation’s history, totaling $1.125 billion.

In recognition of Charles’ intelligence, tenacity and integrity, as well as his unwavering efforts “to uphold the high ideals of justice and rule of law,” Ohio Northern University Pettit College of Law conferred on him the degree of Doctor of Law Honoris Causa. 

Charles joined the Adjunct Faculty at the University of Pittsburgh School of Law in January 2003. He teaches Conflict of Laws. In March 2026, he taught "Law, Ideology, Science and Energy Project Finance" as a guest faculty instructor at Vanderbilt Law School.