"Marbury" also established that the power of judicial review covers actions by the executive branch—the President, his cabinet members, and the departments and agencies they head. However, American courts' power of judicial review over executive branch actions only extends to matters in which the executive has a legal duty to act or refrain from acting, and does not extend to matters that are entirely within the President's discretion, such as whether to veto a bill or whom to appoint to an office. This power has been the basis of many subsequent important Supreme Court decisions in American history, such as the 1974 case "United States v. Nixon", in which the Court held that President Richard Nixon had to comply with a subpoena to provide tapes of his conversations for use in a criminal trial related to the Watergate scandal, and which ultimately led to Nixon's resignation.