Thomas P. O’Brien is a partner and chair of the Los Angeles Litigation Department. Prior to joining Paul Hastings, Mr. O’Brien served as the United States Attorney for the Central District of California, having been appointed by President George W. Bush and unanimously confirmed by the United States Senate. Mr. O’Brien represents corporations and individuals at all phases of government investigations and prosecutions, including federal and state False Claims Act (also known as qui tam matters), Foreign Corrupt Practices Act (“FCPA”), Health Care fraud, and other corporate compliance matters, guiding his clients from their first contact with the DOJ, SEC, state or regulatory authorities through trial. He regularly conducts internal investigations for corporations into potential violations of law or other wrongdoing. He also investigates and advises clients on embezzlement, accounting fraud, and other complex white collar matters.
Mr. O’Brien is a nationally recognized trial attorney. He is a U.S. Fellow with the International Academy of Trial Lawyers, an honor limited to 500 trial attorneys in the United States, a member of the National Trial Lawyers: Top 100, and has been noted by Chambers USA for his “fantastic instincts and courtroom skill.” Mr. O’Brien has successfully tried over 95 cases, both criminal and civil, in federal and state court throughout the nation. 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 unparalleled experience navigating dual civil-criminal proceedings and handling complex, first-of-its-kind matters in multiple jurisdictions, including matters conducted in foreign nations.
During his tenure as United States Attorney, Mr. O’Brien had responsibility over all federal criminal and tax investigations and prosecutions as well as 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 Central District, and increased complex case filings by 50 percent. The office also filed the largest gang RICO case in the history of the Department of Justice and the largest RICO case against a motorcycle gang and, for the first time in the nation, seized the gang’s trademark and filed the largest tax restitution case in IRS history. Mr. O’Brien also served on the President’s Corporate Fraud Task Force and was a member of the Attorney General’s Advisory Committee’s Cyber/Intellectual Property Subcommittee.
Before he was confirmed as United States 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.
Prior to 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 matters, including federal hate crimes, human trafficking violations, and police misconduct cases. Prior to becoming a federal prosecutor, Mr. O’Brien was a Deputy District Attorney in Los Angeles County assigned to the Hardcore Gang Division, where he tried 35 gang murder cases.
Upon graduation from the United States Naval Academy, Mr. O’Brien accumulated over 2,000 flight hours as a Radar Intercept Officer in the F-14A Tomcat fighter with the United States Navy and served on two overseas deployments on active duty. He is a graduate of the United States Navy Fighter Weapons School, commonly known as Topgun.
- Represents a hospital in connection with an investigation by the Department of Justice and Office of the Inspector General into potential violations of the False Claims Act and federal Anti-Kickback Statute.
- Successfully led the defense of a university professor in a high-profile felony prosecution involving alleged labor code violations, which will result in the charges being dismissed. The case garnered national media attention in what has been described as the first case of its kind.
- Represented a major national services corporation in a Department of Justice investigation concerning allegations that the company violated the False Claims Act. The investigation was closed by the Department of Justice with no charges being brought.
- Led a team to effectively defend a local government entity during a two-year DOJ investigation into allegations of corruption in a billion dollar purchasing project.
- Represented a foreign conglomerate in a high-profile criminal matter involving allegations of international trade secret theft in the Eastern District of Virginia.
- Spearheaded the internal investigation of serious allegations of fraud against a medical device manufacturer. At the conclusion of the investigation, made a multi-hour presentation to the government, resulting in the termination of the investigation into the client.
- Assisted in representing a former CEO against allegations that the client engaged in insider trading in connection with a secondary offering. The client was acquitted of all charges at trial.
- Pioneered a novel settlement strategy for a medical device manufacturer to resolve criminal allegations brought against it in connection with alleged Cal OSHA violations.
- Led a federal trial team to a front-page defense victory for a Sheriff’s deputy accused of obstruction of justice. Issues raised during the second trial on the matter are currently before the Ninth Circuit and the court has granted the defense’s motion for bail pending appeal.
- Successfully led a team of attorneys in conducting an internal investigation at the request of a Southern California health center. That investigation, since closed, arose out of allegations that employees of the health center accepted improper benefits in exchange for referrals to certain patient facilities in violation of federal and state anti-kickback statutes.
- Persuaded the Department of Justice not to file charges against a physician with a successful medical practice who was being investigated by the Department of Justice for claims of fraudulent billing. When Mr. O’Brien was brought onto the case, the investigation had been ongoing for several years, and the government had issued a final plea offer and expressed their intention to indict the client. Within weeks, Mr. O’Brien and his team conducted an investigation and presented new evidence to the Department of Justice. The Department of Justice decided to allow the statute of limitations to expire on the charges that they, only weeks earlier, intended to file.
- Victoriously represented the police chief of a local city who faced civil charges filed by the state Attorney General as part of allegations against an entire city council and several administrators for defrauding taxpayers and wasting taxpayer monies. In a case described by numerous media outlets as one of the biggest corruption cases in the nation, and despite the extreme public outcry attacking his client, Mr. O’Brien and his team convinced the court to dismiss the complaint with prejudice.
- Represented a local airport commission in an investigation by the Federal Bureau of Investigation into allegations of corruption. Within months of being retained in this case, Mr. O’Brien managed to focus the government on the actions of other individuals and received a letter from the Department of Justice clearing his client.
Accolades and Recognitions
- Chambers USA, Litigation: White-Collar Crime & Government Investigations
- U.S. Fellow: International Academy of Trial Lawyers (by invitation)
- National Trial Lawyers: Top 100 (by invitation)
- 2008 Immigration and Customs Enforcement Assistant Secretary’s Award for Excellence in Law Enforcement
- 2007 Anti-Defamation League Pacific Southwest Region’s Helene and Joseph Sherwood Prize for combating hate
- 2007 Attorney General’s Award for Exceptional Service—the highest award given by the Attorney General—for his role in investigating and prosecuting street gang members who committed hate-crime murders of African-Americans in Northeast Los Angeles
- 2000 Deputy District Attorney of the Month Award for successfully prosecuting two back-to-back gang murder cases in the month of July
- Received awards from many different organizations, including the Los Angeles City Council; Los Angeles Police Department; Federal Bureau of Investigation; Drug Enforcement Administration; United States Secret Service; Internal Revenue Service; United States Marshal’s Office; Santa Barbara District Attorney’s Office; United States Postal Service; United States Postal Inspectors and Office of Inspector General; Bureau of Alcohol, Tobacco, Firearms and Explosives; and the Los Angeles City Attorney
- University of San Diego School of Law, J.D., 1993 (cum laude, Associate Editor of the San Diego Law Review)
- United States Naval Academy, B.S., 1981