Final answer:
The Supreme Court ruled in the United States v. Nixon case that President Nixon had to release the tapes of his conversations. The ruling established that executive privilege is not absolute.
Step-by-step explanation:
In the case of United States v. Nixon in 1974, the Supreme Court ruled that President Nixon was required to release the actual tapes of his conversations related to the Watergate scandal. The ruling established that the President's claim of executive privilege is not absolute and can be overridden by the need for evidence in a criminal investigation. This ruling played a significant role in holding the President accountable for his actions.