Which Supreme Court case held that executive privilege cannot protect documents in criminal prosecutions?

The case that held that executive privilege cannot protect documents in criminal prosecutions is United States v. Nixon. This landmark Supreme Court decision, decided in 1974, arose from the Watergate scandal when President Nixon was ordered to release tapes and documents related to his conversations during the investigation of the break-in at the Democratic National Committee headquarters.

The Supreme Court ruled that while the President does have a degree of executive privilege to maintain confidentiality in certain matters, this privilege is not absolute. In criminal proceedings, the need for evidence to ensure a fair trial outweighs the President's claim to confidentiality. Therefore, the Court ultimately concluded that the tapes and documents could not remain hidden from the judicial process, setting a significant precedent regarding the limitations of executive privilege in the context of criminal law.

In contrast, the other cases mentioned do not address the concept of executive privilege. For instance, Brown v. Board of Education focuses on the desegregation of public schools, Plessy v. Ferguson addresses racial segregation laws, and Miranda v. Arizona pertains to the rights of individuals in police custody. None of these cases revolve around the issue of executive privilege or its limitations, making United States v. Nixon the relevant choice.