In the early 1970s, several men broke into the Democratic Party's national headquarters at the Watergate building in Washington, D. C. In the investigation that followed, the judge ordered that tapes of conversations that had taken place at the White House be given to the court as evidence. President Nixon refused to turn over the tapes, claiming executive privilege. Executive privilege is a concept that is based on the idea that the president needs to keep some information secret. In United States v. Nixon, the Supreme Court ruled that when the information was important to a criminal case, executive privilege could not be used.