John Terzaken is a partner in Simpson Thacher & Bartlett LLP’s litigation department. He advises US and international clients involved in domestic and cross-border antitrust and other regulatory investigations and litigation. His practice spans government enforcement and private litigation of cartel and other antitrust infringements, market sector investigations and general antitrust compliance, across all industry sectors.

Previously, John was director of criminal enforcement at the US Department of Justice (DOJ), Antitrust Division, where he had management responsibility for the Division’s criminal investigations and litigation nationwide. During his tenure with the Antitrust Division, John investigated, litigated and presided over some of the largest global cartel investigations undertaken by the DOJ. He also served as the Division’s primary liaison with state, federal and foreign law enforcement authorities, and as the Division’s financial fraud coordinator for inter-agency prosecutions, investigations and information sharing. John’s DOJ service earned him awards of distinction from the Attorney General of the United States and the Assistant Attorney General for the Antitrust Division.