dissenting.*
Judge William Campbell, who has been on the District Court in Chicago for over 32 years, recently made the following indictment against the grand jury: 1
“This great institution of the past has long ceased to be the guardian of the people for which purpose it was created at Runnymede. Today it is but a convenient tool for the prosecutor — too often used solely for publicity. Any - experienced prosecutor will admit that he can indict anybody at any timé for almost anything before any grand jury.”
It is, indeed, common knowledge that the grand jury, having been conceived as a bulwark between the citizen and the Government, is now a tool of the Executive. *24The concession by the Court that the grand jury is no longer in a realistic sense “a protective bulwark standing solidly between the ordinary citizen and an overzealous prosecutor” is reason enough to affirm these judgments.
It is not uncommon for witnesses summoned to appear before the grand jury at a designated room to discover that the room is the room of the prosecutor. The cases before us today are prime examples of this perversion.
Respondent Dionisio and approximately 19 others were subpoenaed by the Special February 1971 Grand Jury for the Northern District of Illinois in an investigation of illegal gambling operations. During the investigation, the grand jury had received as exhibits voice recordings obtained under court orders, on warrants issued under 18 U. S. C. § 2518 authorizing wiretaps. The witnesses were instructed to go to the United States Attorney’s office, with their own counsel if they desired, in the company of an FBI agent who had been appointed as an agent of the grand jury by its foreman, and to read the transcript of the wire interception. The readings were recorded. The grand jury then compared the voices taken from the wiretap and the witnesses’ record. Dionisio refused to make the voice exemplars on the ground they would violate his rights under the Fourth and Fifth Amendments. The Government filed petitions in the United States District Court for the Northern District of Illinois to compel the witness to furnish the exemplars to the grand jury. The court rejected the constitutional arguments of the respondent and demanded compliance. Dionisio again refused and was adjudged in civil contempt and placed in prison until he obeyed the court order or until the term of the special grand jury expired. The Court of Appeals reversed, concluding that to compel compliance would violate his Fourth Amendment rights. It held that voice exemplars are protected by the Constitution from un*25reasonable seizures and that the Government failed to show the reasonableness of its actions.
The Special September 1971 Grand Jury, also in the Northern District of Illinois, was convened to investigate thefts of interstate shipments of goods that occurred in the State. Respondent Mara was subpoenaed and was requested to submit a sample of his handwriting before the grand jury. Mara refused. The Government went to the District Court for the Northern District of Illinois, asserting to the court that the handwriting exemplars were “essential and necessary” to the investigation. In an in camera proceeding, the Court held that the witness must comply with the request of the grand jury. The Court of Appeals reversed on the basis of its decision in In re Dionisio. It outlined the procedures the Government must follow in cases of this kind. First, the hearing to determine the constitutionality of the seizure must be held in open court in an adversary manner. Substantially, the Government must show that the grand jury was properly authorized to investigate a matter that Congress had power to regulate, that the information sought was relevant to the inquiry, and that the grand jury’s request for exemplars was adequate, but not excessive, for the purposes of the relevant inquiry.
Today, the majority overrules this reasoned opinion of the Seventh Circuit.
Under the Fourth Amendment, law enforcement officers may not compel the production of evidence, absent a showing of the reasonableness of the seizure. Davis v. Mississippi, 394 U. S. 721; Boyd v. United States, 116 U. S. 616. The test protects the person’s expectation of privacy over the thing. We said in Katz v. United States, “the Fourth Amendment protects people, not places. What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth *26Amendment protection. . . . But what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.” 389 U. S. 347, 351-352. The Government asserts that handwriting and voice exemplars do not invade the privacy of an individual when taken because they are physical characteristics that are exposed to the public. It argues that, unless the person involved is a recluse, these characteristics are not meant to be private to the individual and thus do not qualify for the aid of the Fourth Amendment.
This Court has held that fingerprints are subject to the requirements of the Search and Seizure Clause of the Fourth Amendment, Davis v. Mississippi, supra. On the other hand, facial scars, birthmarks, and other facial features have been said to be “in plain view” and not protected. United States v. Doe (Schwartz), 457 F. 2d 895.
In Davis, the sheriff in Mississippi rounded up 24 blacks when a rape victim described her assailant only as a young Negro. Each was fingerprinted and then released. Davis was presented to the victim but was not identified. He was jailed without probable cause, and only later did the FBI confirm that his fingerprints matched those on the window of the victim’s home. The Court held that the fingerprints could not be admitted, as they were seized without reasonable grounds. “Investigatory seizures would subject unlimited numbers of innocent persons to the harassment and ignominy incident to involuntary detention. Nothing is more clear than that the Fourth Amendment was meant to prevent wholesale intrusions upon the personal security of our citizenry, whether these intrusions be termed 'arrests’ or 'investigatory detentions.’ ” Davis v. Mississippi, supra, at 726-727. The dragnet effect in Dionisio, where approximately 20 people were subpoenaed *27for purposes of identification, was just the kind of invasion that the Davis case sought to prevent. Facial features can be presented to the public regardless of the cooperation or compulsion of the owner of the features. But to get the exemplars, the individual must be involved. So, although a person’s handwriting is used in everyday life and speech is the vehicle of normal social intercourse, when these personal characteristics are sought for purposes of identification, the Government enters the zone of privacy and, in my view, must make a showing of reasonableness before seizures may be made.
The Government contends that since the production was before the grand jury, a different standard of constitutional law exists because the grand jury has broad investigatory powers. Blair v. United States, 250 U. S. 273. Cf. United States v. Bryan, 339 U. S. 323. The Government concedes that the Fourth Amendment applies to the grand jury and prevents it from executing subpoenas duces tecum that are overly broad. Hale v. Henkel, 201 U. S. 43, 76. It asserts, however, that that is the limit of its application. But the Fourth Amendment is not so limited, as this Court has held in Davis, supra, and reiterated in Terry v. Ohio, 392 U. S. 1, where it held that the Amendment comes into effect whether or not there is a fullblown search. The essential purpose is to extend its protection “wherever an individual may harbor a reasonable 'expectation of privacy.’ ” Id., at 9.
Just as the nature of the Amendment rebels against the limits that the Government seeks to impose on its coverage, so does the nature of the grand jury itself. It was secured at Runnymede from King John as a cornerstone of the liberty of the people. It was to serve as a buffer between the state and the offender. For no matter how obnoxious a person may be, the United States cannot prosecute for a felony without an indict*28ment. The individual is therefore protected by a body of his peers who have no axes to grind or any Government agency to serve. It is the only accusatorial body of the Federal Government recognized by the Constitution. “The very purpose of the requirement that a man be indicted by grand jury is to limit his jeopardy to offenses charged by a group of his fellow citizens acting independently of either prosecuting attorney or judge.” 2 Stirone v. United States, 361 U. S. 212, 218. But here, as the Court of Appeals said, “It is evident that the grand jury is seeking to obtain the voice exemplars of the witnesses by the use of its subpoena powers because probable cause did not exist for their arrest or for some other, less unusual, method of compelling the production of the exemplars.” In re Dionisio, 442 F. 2d 276, 280. See *29Hannah v. Larche, 363 U. S. 420, 497-499 (Douglas, J., dissenting). Are we to stand still and watch the prosecution evade its own constitutional restrictions on its powers by turning the grand jury into its agent? Are we to allow the Government to usurp powers that were granted to the people by the Magna Carta and codified in our Constitution? That will be the result of the majority opinion unless we continue to apply to the grand jury the protection of the Fourth Amendment.
As the Court stated in Hale v. Henkel, 201 U. S., at 59, “the most valuable function of the grand jury” was “to stand between the prosecutor and the accused, and to determine whether the charge was founded upon credible testimony or was dictated by malice or personal ill will.”
The Court held in that case that the Fourth Amendment was applicable to grand jury proceedings and that a sweeping, all-inclusive subpoena was “equally indefensible as a search warrant would be if couched in similar terms.” Id., at 77.
Of course, the grand jury can require people to testify. Hale v. Henkel makes plain that proceedings before the grand jury do not carry all of the impedimenta of a trial before a petit jury. To date, the grand jury cases have involved only testimonial evidence. To say, as the Government suggests, that nontestimonial evidence is free from any restraint imposed by the Fourth Amendment is to give those who today manipulate grand juries vast and uncontrollable power.
The Executive, acting through a prosecutor, could not have obtained these exemplars as it chose, for as stated by the Court of Appeals for the Eighth Circuit, “We conclude that the taking of the handwriting exemplars . . . was a search and seizure under the Fourth Amendment.” United States v. Harris, 453 F. 2d 1317, 1319. As Katz v. United States, supra, makes plain, the searches that may be made without prior approval by judge or magis*30trate are “subject only to a few specifically established and well-delineated exceptions.” 389 U. S., at 357.
The showing required by the Court of Appeals in the Mara case was that the Government’s showing of need for the exemplars be “reasonable,” which “is not necessarily synonymous with probable cause.” 454 F. 2d 580, 584. When we come to grand juries, probable cause in the strict Fourth Amendment meaning of the term does not have in it the same ingredients pointing toward guilt as it does in the arrest and trial of people. In terms of probable cause in the setting of the grand jury, the question is whether the exemplar sought is in some way connected with the suspected criminal activity under investigation. Certainly less than that showing would permit the Fourth Amendment to be robbed of all of its vitality.
In the Mara case, the prosecutor submitted to the District Court an affidavit of a Government investigator stating the need for the exemplar based on his investigation. The District Court passed on the matter in camera, not showing the affidavit to either respondent or his counsel. The Court of Appeals, relying on Alderman v. United States, 394 U. S. 165, 183, held that in such cases there should be an adversary proceeding. 454 F. 2d, at 582-583. If “reasonable cause” is to play any function in curbing the executive appetite to manipulate grand juries, there must be an opportunity for a showing that there was no “reasonable cause.” As we stated in Aider-man: “Adversary proceedings will not magically eliminate all error, but they will substantially reduce its incidence by guarding against the possibility that the trial judge, through lack of time or unfamiliarity with the information contained in and suggested by the materials, will be unable to provide the scrutiny which the Fourth *31Amendment exclusionary rule demands.” 394 U. S., at 184.
The District Court in the Dionisio case went part way by allowing the witness to have his counsel present when the voice exemplars were prepared in the prosecutor’s office. 442 F. 2d, at 278. The Court of Appeals acted in a traditionally fair way when it ruled that the reasonableness of a prosecutor’s request for exemplars be put down for an adversary hearing before the District Court. It would be a travesty of justice to allow the prosecutor to do under the cloak of the grand jury what he could not do on his own.
In view of the disposition which I would make of these cases, I need not reach the Fifth Amendment question. But lest there be any doubt as to where I stand, I adhere to my position in United States v. Wade, 388 U. S. 218, 243 (separate statement), and in Schmerber v. California, 384 U. S. 757, 773 (Black, J., dissenting, joined by Douglas, J.), 778 (Douglas, J., dissenting), to the effect that the Fifth Amendment is not restricted to testimonial compulsion.
This opinion applies also to No. 71-229, United States v. Dionisio, ante, p. 1.
55 F. R. D. 229, 253 (1972).
As Mr. Justice Black said in In re Groban, 352 U. S. 330, 346-347:
“The traditional English and American grand jury is composed of 12 to 23 members selected from the general citizenry of the locality where the alleged crime was committed. They bring into the grand jury room the experience, knowledge and viewpoint of all sections of the community. They have no axes to grind and are not charged personally with the administration of the law. No one of them is a prosecuting attorney or law-enforcement officer ferreting out crime. It would be very difficult for officers of the state seriously to abuse or deceive a witness in the presence of the grand jury. Similarly the presence of the jurors offers a substantial safeguard against the officers’ misrepresentation, unintentional or otherwise, of the witness’ statements and conduct before the grand jury. The witness can call on the grand jurors if need be for their normally unbiased testimony as to what occurred before them.”
Although that excerpt is from a dissent on the particular facts of the case, there could be no disagreement as to the accuracy of the description of the grand jury’s historical function.
The tendency is for government to use shortcuts in its search for instruments more susceptible to its manipulation than is the historic grand jury. See Hannah v. Larche, 363 U. S. 420, 505 (Douglas, J., dissenting); Jenkins v. McKeithen, 395 U. S. 411.