How did the Supreme Court ruling in United States versus Nixon check presidential power?

The Supreme Court ruling in United States v. Nixon checked presidential power by establishing the principle that the President does not have absolute immunity and is not above the law. In this case, the Court ruled that President Nixon was required to hand over the Watergate tapes as evidence in a criminal investigation, despite his claims of executive privilege.

This decision set a precedent that even the President must comply with judicial orders and that executive privilege is not unlimited. It demonstrated that the President cannot use his authority to shield himself from legal consequences or obstruct justice. Overall, the ruling in United States v. Nixon reaffirmed the system of checks and balances by affirming the judiciary's ability to hold the President accountable to the rule of law.