John Choon Yoo (born June 10, 1967 in Seoul) is an American attorney and former official in the United States Department of Justice.
He has been a professor of law at the University of California, Berkeley's School of Law (Boalt Hall) since 1993. He is currently serving as a visiting professor of law at the Chapman University School of Law in Orange County, California. Yoo has authored two books on presidential power and the war on terrorism, as well as numerous journal and newspaper articles. He has held the Fulbright Distinguished Chair in Law at the University of Trento and has also been a visiting law professor at the Free University of Amsterdam and the University of Chicago. Since 2003, Yoo has also worked as a visiting scholar at the American Enterprise Institute, a conservative and libertarian think tank. He also writes a monthly column, entitled Closing Arguments, for The Philadelphia Inquirer.
Yoo, a member of the Pennsylvania State Bar, was a law clerk for Appeals Court judge Laurence H. Silberman and for Supreme Court Justice Clarence Thomas. He also served for a time as general counsel of the Senate Judiciary Committee. Yoo is best known for his work from 2001 to 2003 in the Department of Justice's Office of Legal Counsel under the George W. Bush Administration. In the Justice Department, Yoo's expansive view of Presidential power led to a close relationship with the office of Vice President Dick Cheney. Yoo played a significant role in the legal justification for the Bush Administration's policy in the War on Terrorism, arguing that prisoner of war status under the Geneva Conventions does not apply to "enemy combatants" captured during the War in Afghanistan and held at the Guantanamo Bay detention camp, asserting executive authority to undertake waterboarding and other "enhanced interrogation techniques" regarded as torture by the current Justice Department. Yoo furthermore argued that the President was not bound by the War Crimes Act, and provided a legal opinion backing the Bush Administration's warrantless wiretapping program.