Mr. Justice Stewart
delivered the opinion of the Court.
The respondent, Richard J. Mara, was subpoenaed to appear before the September 1971 Grand Jury in the Northern District of Illinois that was investigating thefts of interstate shipments. On two separate occasions he was directed to produce handwriting and printing exemplars to the grand jury’s designated agent. Each time he was advised that he was a potential defendant in the matter under investigation. On both occasions he refused to produce the exemplars.
The Government then petitioned the United States District Court to compel Mara to furnish the handwriting and printing exemplars to the grand jury. The petition indicated that the exemplars were “essential and necessary” to the grand jury investigation and would be used solely as a standard of comparison to determine whether Mara was the author of certain writings. The petition was accompanied by an affidavit of an FBI agent, submitted in camera, which set forth the basis for seeking the exemplars. The District Judge rejected the respondent’s contention that the compelled production of such exemplars would constitute an unreasonable search and seizure, and he ordered the respondent to provide them. When the witness continued to refuse to do so, he was adjudged to be in civil contempt and was committed to custody until he obeyed the court order or until the expiration of the grand jury term.
The Court of Appeals for the Seventh Circuit reversed. 454 F. 2d 580. Relying on its earlier decision in In re Dionisio, 442 F. 2d 276, rev’d, ante, p. 1, the court found that the directive to furnish the exemplars would constitute an unreasonable search and seizure. “[I]t is plain that compelling [Mara] to furnish exemplars of his handwriting and printing is forbidden by the Fourth Amendment unless the Government has complied with its reasonableness requirement . . . 454 F. 2d, at 582.
The court then turned to two issues necessarily generated by its decision in Dionisio — the procedure the Government must follow and the substantive showing it must make to establish the reasonableness of the grand jury's directive. It rejected the in camera procedure of the District Court, and held that the Government would have to present its affidavit in open court in order that Mara might contest its sufficiency. The court ruled that to establish “reasonableness” the Government would have to make a substantive showing: “that the grand jury investigation was properly authorized, for a purpose Congress can order, that the information sought is relevant to the inquiry, and that . . . the grand jury process is not being abused. . . . [T]he Government’s affidavit must also show why satisfactory handwriting and printing exemplars cannot be obtained from other sources without grand jury compulsion.” 454 F. 2d, at 584^585.
We granted certiorari, 406 U. S. 956, to consider this case with United States v. Dionisio, No. 71-229, ante, p. 1.
We have held today in Dionisio, that a grand jury subpoena is not a “seizure” within the meaning of the Fourth Amendment and, further, that that Amendment is not violated by a grand jury directive compelling production of “physical characteristics” that are “constantly exposed to the public.” Ante, at 9, 10, 14. Handwriting, like speech, is repeatedly shown to the public, and there is no more expectation of privacy in the physical characteristics of a person’s script than there is in the tone of his voice. See United States v. Doe (Schwartz), 457 F. 2d 895, 898-899; Bradford v. United States, 413 F. 2d 467, 471-472; cf. Gilbert v. California, 388 U. S. 263, 266-267. Consequently the Government was under no obligation here, any more than in Dionisio, to make a preliminary showing of ‘ ‘reasonableness. ’ ’
Indeed, this case lacks even the aspects of an expansive investigation that the Court of Appeals found significant in Dionisio. In that case, 20 witnesses were summoned to give exemplars; here there was only one. The specific and narrowly drawn directive requiring the witness to furnish a specimen of his handwriting violated no legitimate Fourth Amendment interest. The District Court was correct, therefore, in ordering the respondent to comply with the grand jury’s request.
Accordingly, the judgment of the Court of Appeals is reversed, and this case is remanded to that court for further proceedings consistent with this opinion.
It is so ordered.
The respondent contends that because he has seen neither the affidavit nor the writings in the grand jury's possession, the Government may actually be seeking “testimonial” communications — the content as opposed to the physical characteristics of his writing. But the Government’s petition for the order to compel production stated: “Such exemplars will be used solely as a standard of comparison in order to determine whether the witness is the author of certain writings.” If the Government should seek more than the physical characteristics of the witness’ handwriting — if, for example, it should seek to obtain written answers to incriminating questions or a signature on an incriminating statement — then, of course, the witness could assert his Fifth Amendment privilege against compulsory self-incrimination.