Final answer:
The Supreme Court may overturn a president's claim of executive privilege to ensure evidence for criminal trials, maintain government transparency and accountability, and when the claim exceeds the powers granted by Congress or the Constitution. The Court also rules that executive privilege is not absolute and cannot be used to avoid legal proceedings.
Step-by-step explanation:
The Supreme Court may overturn claims of executive privilege by the president under several circumstances. One such instance is when there is a need to ensure available evidence for a criminal trial, as seen in United States v. Nixon, where the Court ordered President Nixon to turn over tape recordings.
Another situation might involve protecting the transparency and accountability of the executive branch, especially if there is an absence of a national security risk or if the privilege is invoked to conceal wrongdoing. The Court generally requires compelling evidence of a significant public interest or constitutional protection to outweigh the president's privilege.
Moreover, the Court often looks at congressional action or inaction to define the parameters of executive privilege. For instance, during the Korean War President Truman's attempt to claim inherent emergency powers to seize steel mills was rejected by the Supreme Court, affirming that presidential powers must stem from the Constitution or Congress. Lastly, the Court has also held that executive privilege is not absolute and may not be used to avoid legal proceedings such as prosecutions and certain civil suits.