Ellen S. Cooper has been an Assistant Attorney General in the Antitrust Division of the Maryland Attorney General's Office since 1985. In 1987, Attorney General J. Joseph Curran, Jr. awarded her an Exceptional Service Award. In 1989, she became Deputy Chief, and in September 1992, she became Chief of Maryland's Antitrust Division. In 2006, Cooper received the Robbins Exceptional Career Service Award. Cooper has been active for many years in the Multistate Antitrust Task Force of the National Association of Attorneys General. In 1993 she received the Marvin Award from the Association for her contributions to NAAG.
Cooper has worked on cases involving the insurance industry, the pharmaceutical industry and high tech industries. Working with the Technical Committee, she monitored Microsoft’s antitrust compliance on behalf of Maryland and a group of other states.
Cooper is author of law review articles on consumer antitrust recoveries, and on the antitrust issues in the pharmaceutical industry. She has also authored a number of articles on state antitrust enforcement published in the Maryland Bar Journal, and in ABA publications.