United States v. Calandra

Justice Powell wrote the opinion for the majority. A grand jury hearing is an investigation to determine if a crime has been committed and whether criminal proceedings should take place. If a grand jury feels that criminal proceedings should occur, it will present to the court an indictment, a written accusation made upon oath. Powell noted that the operation of a grand jury is generally unrestrained by the technical, procedural, and evidentiary rules that are used in criminal trials. An indictment is not subject to a challenge that the grand jury acted on inadequate evidence or on information obtained in violation of a defendant's Fifth Amendment privilege against self-incrimination. Powell explained that the exclusionary rule was adopted to guard against unreasonable searches and seizures, which are forbidden by the Fourth Amendment. Powell noted that the "rule's prime purpose is to deter future unlawful police conduct." The rule is a remedy designed to safeguard Fourth Amendment rights through its deterrent effect, "rather than a personal constitutional right of the party aggrieved." The exclusionary rule has never been interpreted to forbid the use of illegally seized evidence at all times.

Regarding grand juries and the exclusionary rule, Powell explained that "we must weigh the potential injury to the historic role and functions of the grand jury against the potential benefits of the rule." Extending the exclusionary rule to grand jury proceedings would seriously impede grand juries. Suppression hearings would halt the progress of a grand jury investigation. Extending the exclusionary rule to grand jury evidence would deter police investigation that was directed toward finding evidence only for grand jury use. Since evidence obtained unlawfully would not be admissible in a criminal trial, a prosecutor would probably not ask for an indictment in a case where a conviction could not be gained.

Calandra claimed that the grand jury's questions invaded his privacy and because the questions were based on illegally obtained evidence, they violated his Fourth Amendment rights. Powell disagreed. The wrong done to Calandra took place during the original search and seizure. Grand jury questions based on evidence from that incident "involve no independent governmental invasion . . . , but rather the usual abridgment of personal privacy common to all grand jury questioning." Grand jury questions based on unlawfully obtained evidence are only a "derivative use" of that evidence. Powell summed up by stating that the damage to grand juries that would be done by extending the use of the exclusionary rule would outweigh the benefit as a deterrent to police misconduct.