Thomas P. O’Brien is a Litigation partner with Paul Hastings in Los Angeles. Prior to joining Paul Hastings, Mr. O’Brien served as the United States Attorney for the Central District of California, after being appointed by President George W. Bush and confirmed by the United States Senate. He routinely advises and represents corporations in high-profile federal and state investigations, including federal and state False Claims Act (also known as qui tam matters), Foreign Corrupt Practices Act (“FCPA”), and other corporate compliance matters, and oversees complex civil and criminal litigation matters.
Mr. O’Brien has vast experience as a trial attorney and has tried over 95 cases, both criminal and civil, in federal and state court. He has represented national and multi-national companies in civil actions with billions of dollars in dispute, and has successfully represented individual corporate leaders and foreign heads of state in civil, criminal, and regulatory proceedings. He has experience navigating dual civil-criminal proceedings and handling complex, first-of-its-kind matters in multiple jurisdictions.
In addition, Mr. O’Brien represents corporations and individuals at all phases of government investigations and prosecutions, guiding his clients from their first contact with the DOJ, SEC, state or regulatory authorities through trial. He regularly counsels clients as they conduct internal investigations into potential violations of law or other wrongdoing. He also investigates and advises clients on embezzlement, accounting fraud, and other complex white collar matters.
During his tenure as U.S. Attorney, Mr. O’Brien was responsible for federal criminal and tax investigations and prosecutions and all civil matters involving the United States, including civil fraud and False Claims Act matters, in the largest federal district in the country. Under his leadership, the office filed the most felony cases in the history of the district, and increased complex case filings by 50 percent. The office also filed the largest RICO case ever against a motorcycle gang and, for the first time in the nation, seized that gang’s trademark.
Before he was confirmed as U.S. Attorney, Mr. O’Brien served for more than two years as the chief of the Criminal Division. In that capacity, he oversaw several high-profile espionage cases, helped bring the first treason case in the nation since World War II, supervised several high-profile public corruption and civil rights cases, charged several cyber crime statutes which had not been charged in the nation, and executed some of the largest fraud cases in the United States. He was the only criminal chief in many years who tried cases during his tenure.
Before serving as Criminal Chief, he was an Assistant United States Attorney for four years before rising to Chief of the Civil Rights Section, where he personally investigated and prosecuted numerous cases, including federal hate crimes, human trafficking violations, and police misconduct cases.