Allen's practice includes advising clients on mergers and acquisitions, providing counseling on non-merger matters, and representing clients in federal court, before the federal antitrust agencies and Congress. He has extensive experience in a range of industries, including media and entertainment, telecommunications, finance and insurance.

Allen joined the firm after spending more than a decade at the U.S. Department of Justice Antitrust Division, where he led many merger and civil non-merger investigations in radio, television, newspapers, motion pictures, and other industries. He was part of the litigation team in a number of important cases brought by the United States, including United States v. Alex. Brown & Sons (NASDAQ Market Makers) and United States v. National Association of Realtors.

Allen currently serves as Chair of the Antitrust Committee of the Bar Association of the District of Columbia and is on the Advisory Boards of the American Antitrust Institute in Washington, D.C. and the Institute for Consumer Antitrust Studies at Loyola University Chicago School of Law. In the past he served as a committee Vice Chair on government antitrust litigation with the ABA’s Antitrust Section, as a resident advisor to the Competition Commission of the Republic of South Africa, and on the advisory panel of the Arts Industries Policy Forum at Vanderbilt University’s Curb Center for Art, Enterprise, and Public Policy. He writes and speaks frequently on antitrust topics.

Prior to joining the Antitrust Division, Allen practiced law in Cincinnati, Ohio with the firm of Waite, Schneider, Bayless and Chesley, and was an adjunct professor at the University of Cincinnati College of Law.