Peter Keisler

Practice Areas

PETER KEISLER has successfully represented some of the country’s largest companies in the telecommunications, transportation, energy and healthcare industries, as well as a host of national trade associations, providing extensive insight and experience gained from his more than 30 years of private and public sector experience. Peter has argued a wide range of federal constitutional, statutory and administrative law cases. His practice representing clients before the U.S. Supreme Court, federal courts of appeals and federal district courts has included the leading role in the nation’s most important and successful commercial and regulatory cases of the past several years, including United States of America v. AT&T & Time Warner, UARG v. EPA, and AEP v. Connecticut. United States of America v. AT&T & Time Warner was one of the most prominent antitrust cases in recent memory. Peter successfully represented AT&T in the Justice Department’s appeal of the District Court decision rejecting the government’s attempt to enjoin AT&T’s acquisition of Time Warner. This was the first time in more than four decades that the government litigated to judgment a challenge to a vertical merger.

Peter started his career at Sidley as an associate in 1989 after completing a clerkship for Justice Anthony Kennedy. In 2002 he joined the Department of Justice (DOJ) as the Principal Deputy Associate Attorney General. Peter spent most of his more than five-year tenure at DOJ as the Assistant Attorney General for the Civil Division, and ultimately served as Acting Attorney General of the United States. He returned to Sidley in 2008.