John has considerable experience litigating in the Supreme Court and the federal courts of appeals, and has substantial knowledge on constitutional, criminal, administrative, employment, and environmental issues. Before joining the firm, John served in senior-level positions in the U.S. Department of Justice. Beginning as an Assistant to the Solicitor General, and continuing with the firm, he has briefed or argued more than a dozen merits cases before the Supreme Court of the United States, and has briefed over 100 cases at the certiorari stage. As the senior Deputy in the Office of Legal Counsel, he advised the White House and senior agency officials on a range of constitutional, statutory, and regulatory matters. John represented the Justice Department as an ex officio member of the U.S. Sentencing Commission and as a member of the Advisory Committee on Federal Rules of Criminal Procedure. John also has argued numerous cases in the federal courts of appeals and tried several criminal cases in federal district court.
The 2010 edition of Chambers USA reports that "Clients consider [John's] addition 'an immediate enhancement to Vinson & Elkins's appellate group: he is a much-loved and widely respected lawyer who is quick on his feet.'"
John has received both the Attorney General's Award for Exceptional Service and the Attorney General's Award for Distinguished Service - the Justice Department's two top awards for lawyers.