Mapp v. Ohio (1961)

This case established that in criminal trials at both the federal and state level, all evidence obtained by police in violation of the Fourth Amendment’s warrant requirement cannot be used against the defendant in court. The Court held, “all evidence obtained by searches and seizures in violation of the Constitution is… inadmissible in a state court.” This is known as the “exclusionary rule.”

This case touched on constitutional principles including separation of powers and checks and balances.