opinion: Opinion of the Court by
  Mr. Justice White,
  announced by Mr. Justice Blackmun.
  These cases arise out of the investigation by a federal grand jury into possible criminal conduct with respect to the release and publication of a classified Defense Department study entitled History of the United States Decision-Making Process on Viet Nam Policy. This document, popularly known as the Pentagon Papers, bore a Defense security classification of Top Secret-Sensitive. The crimes being investigated included the retention of public property or records with intent to convert (18 U. S. C. § 641), the gathering and transmitting of national defense information (18 U. S. C. § 793), the concealment or removal of public records or documents (18 U. S. C. § 2071), and conspiracy to commit such offenses and to defraud the United States (18 U. S. C. §371).
  Among the witnesses subpoenaed were Leonard S. Rodberg, an assistant to Senator Mike Gravel of Alaska and a resident fellow at the Institute of Policy Studies, and Howard Webber, Director of M. I. T. Press. Senator Gravel, as intervenor, filed motions to quash the subpoenas and to require the Government to specify the particular questions to be addressed to Rodberg. He asserted that requiring these witnesses to appear and testify would violate his privilege under the Speech or Debate Clause of the United States Constitution, Art. I, § 6, cl. 1.
  It appeared that on the night of June 29, 1971, Senator Gravel, as Chairman of the Subcommittee on Buildings and Grounds of the Senate Public Works Committee, convened a meeting of the subcommittee and there read extensively from a copy of the Pentagon Papers. He then placed the entire 47 volumes of the study in the public record. Rodberg had been added to the Senator’s staff earlier in the day and assisted Gravel in preparing for and conducting the hearing. Some weeks later there were press reports that Gravel had arranged for the papers to be published by Beacon Press and that members of Gravel’s staff had talked with Webber as editor of M. I. T. Press.
  The District Court overruled the motions to quash and to specify questions but entered an order proscribing certain categories of questions. United States v. Doe, 332 F. Supp. 930 (Mass. 1971). The Government’s contention that for purposes of applying the Speech or Debate Clause the courts were free to inquire into the regularity of the subcommittee meeting was rejected. Because the Clause protected all legislative acts, it was held to shield from inquiry anything the Senator did at the subcommittee meeting and “certain acts done in preparation therefor.” Id., at 935. The Senator’s privilege also prohibited “inquiry into things done by Dr. Rodberg as the Senator’s agent or assistant which would have been legislative acts, and therefore privileged, if performed by the Senator personally.” Id., at 937-938. The trial court, however, held the private publication of the documents was not privileged by the Speech or Debate Clause. Id., at 936.
  The Court of Appeals affirmed the denial of the motions to quash but modified the protective order to reflect its own views of the scope of the congressional privilege. United States v. Doe, 455 F. 2d 753 (CA1 1972). Agreeing that Senator and aide were one for the purposes of the Speech or Debate Clause and that the Clause foreclosed inquiry of both Senator and aide with respect to legislative acts, the Court of Appeals also viewed the privilege as barring direct inquiry of the Senator or his aide, but not of third parties, as to the sources of the Senator’s information used in performing legislative duties. Although it did not consider private publication by the Senator or Beacon Press to be protected by the Constitution, the Court of Appeals apparently held that neither Senator nor aide could be questioned about it because of a common-law privilege akin to the judicially created immunity of executive officers from liability for libel contained in a news release issued in the course of their normal duties. See Barr v. Matteo, 360 U. S. 564 (1959). This privilege, fashioned by the Court of Appeals, would not protect third parties from similar inquiries before the grand jury. As modified by the Court of Appeals, the protective order to be observed by prosecution and grand jury was:
  “(1) No witness before the grand jury currently investigating the release of the Pentagon Papers may be questioned about Senator Mike Gravel’s conduct at a meeting of the Subcommittee on Public Buildings and Grounds on June 29, 1971, nor, if the questions are directed to the motives or purposes behind the Senator’s conduct at that meeting, about any communications with him or with his aides regarding the activities of the Senator or his aides during the period of their employment, in preparation for and related to said meeting.
  “(2) Dr. Leonard S. Rodberg may not be questioned about his own actions in the broadest sense, including observations and communications, oral or written, by or to him or coming to his attention while being interviewed for, or after having been engaged as a member of Senator Gravel’s personal staff to the extent that they were in the course of his employment.”
  The United States petitioned for certiorari challenging the ruling that aides and other persons may not be questioned with respect to legislative acts and that an aide to a Member of Congress has a common-law privilege not to testify before a grand jury with respect to private publication of materials introduced into a subcommittee record. Senator Gravel also petitioned for certiorari seeking reversal of the Court of Appeals insofar as it held private publication unprotected by the Speech or Debate Clause and asserting that the protective order of the Court of Appeals too narrowly protected against inquiries that a grand jury could direct to third parties. We granted both petitions. 405 U. S. 916 (1972).
  I
  Because the claim is that a Member’s aide shares the Member’s constitutional privilege, we consider first whether and to what extent Senator Gravel himself is exempt from process or inquiry by a grand jury investigating the commission of a crime. Our frame of reference is Art. I, § 6, cl. 1, of the Constitution:
  “The Senators and Representatives shall receive a Compensation for their Services, to be ascertained by Law, and paid out of the Treasury of the United States. They shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.”
  The last sentence of the Clause provides Members of Congress with two distinct privileges. Except in cases of “Treason, Felony and Breach of the Peace,” the Clause shields Members from arrest while attending or traveling to and from a session of their House. History reveals, and prior cases so hold, that this part of the Clause exempts Members from arrest in civil cases only. “When the Constitution was adopted, arrests in civil suits were still common in America. It is only to such arrests that the provision applies.” Long v. Ansell, 293 U. S. 76, 83 (1934) (footnote omitted). “Since . . . the terms treason, felony and breach of the peace, as used in the constitutional provision relied upon, excepts from the operation of the privilege all criminal offenses, the conclusion results that the claim of privilege of exemption from arrest and sentence was without merit . . . .” Williamson v. United States, 207 U. S. 425, 446 (1908). Nor does freedom from arrest confer immunity on a Member from service of process as a defendant in civil matters, Long v. Ansell, supra, at 82-83, or as a witness in a criminal case. “The constitution givés to every man, charged with an offence, the benefit of compulsory process, to secure the attendance of his witnesses. I do not know of any privilege to exempt members of congress from the service, or the obligations, of a subpoena, in such cases.” United States v. Cooper, 4 Dall. 341 (1800) (Chase, J., sitting on Circuit). It is, therefore, sufficiently plain that the constitutional freedom from arrest does not exempt Members of Congress from the operation of the ordinary criminal laws, even though imprisonment may prevent or interfere with the performance of their duties as Members. Williamson v. United States, supra; cf. Burton v. United States, 202 U. S. 344 (1906). Indeed, implicit in the narrow scope of the privilege of freedom from arrest is, as Jefferson noted, the judgment that legislators ought not to stand above the law they create but ought generally to be bound by it as are ordinary persons. T. Jefferson, Manual of Parliamentary Practice, S. Doc. No. 92-1, p. 437 (1971).
  In recognition, no doubt, of the force of this part of § 6, Senator Gravel disavows any assertion of general immunity from the criminal law. But he points out that the last portion of § 6 affords Members of Congress another vital privilege — they may not be questioned in any other place for any speech or debate in either House. The claim is not that while one part of § 6 generally permits prosecutions for treason, felony, and breach of the peace, another part nevertheless broadly forbids them. Rather, his insistence is that the Speech or Debate Clause at the very least protects him from criminal or civil liability and from questioning elsewhere than in the Senate, with respect to the events occurring at the subcommittee hearing at which the Pentagon Papers were introduced into the public record. To us this claim is incontrovertible. The Speech or Debate Clause was designed to assure a co-equal branch of the government wide freedom of speech, debate, and deliberation without intimidation or threats from the Executive Branch. It thus protects Members against prosecutions that directly impinge upon or threaten the legislative process. We have no doubt that Senator Gravel may not be made to answer — either in terms of questions or in terms of defending himself from prosecution — for the events that occurred at the subcommittee meeting. Our decision is made easier by the fact that the United States appears to have abandoned whatever position it took to the contrary in the lower courts.
  Even so, the United States strongly urges that because the Speech or Debate Clause confers a privilege only upon “Senators and Representatives,” Rodberg himself has no valid claim to constitutional immunity from grand jury inquiry. In our view, both courts below correctly rejected this position. We agree with the Court of Appeals that for the purpose of construing the privilege a Member and his aide are to be “treated as one,” United States v. Doe, 455 F. 2d, at 761; or, as the District Court put it: the “Speech or Debate Clause prohibits inquiry into things done by Dr. Rodberg as the Senator’s agent or assistant which would have been legislative acts, and therefore privileged, if performed by the Senator personally.” United States v. Doe, 332 F. Supp., at 937-938. Both courts recognized what the Senate of the United States urgently presses here: that it is literally impossible, in view of the complexities of the modern legislative process, with Congress almost constantly in session and matters of legislative concern constantly proliferating, for Members of Congress to perform their legislative tasks without the help of aides and assistants; that the day-to-day work of such aides is so critical to the Members’ performance that they must be treated as the latter’s alter egos; and that if they are not so recognized, the central role of the Speech or Debate Clause — to prevent intimidation of legislators by the Executive and accountability before a possibly hostile judiciary, United States v. Johnson, 383 U. S. 169, 181 (1966) — will inevitably be diminished and frustrated.
  The Court has already embraced similar views in Barr v. Matteo, 360 U. S. 564 (1959), where, in immunizing the Acting Director of the Office of Rent Stabilization from liability for an alleged libel contained in a press release, the Court held that the executive privilege recognized in prior cases could not be restricted to those of cabinet rank. As stated by Mr. Justice Harlan, the “privilege is not a badge or emolument of exalted office, but an expression of a policy designed to aid in the effective functioning of government. The complexities and magnitude of governmental activity have become so great that there must of necessity be a delegation and re-delegation of authority as to many functions, and we cannot say that these functions become less important simply because they are exercised by officers of lower rank in the executive hierarchy.” Id., at 572-573 (footnote omitted).
  It is true that the Clause itself mentions only “Senators and Representatives,” but prior cases have plainly not taken a literalistic approach in applying the privilege. The Clause also speaks only of “Speech or Debate,” but the Court’s consistent approach has been that to confine the protection of the Speech or Debate Clause to words spoken in debate would be an unacceptably narrow view. Committee reports, resolutions, and the act of voting are equally covered; “[i]n short, . . . things generally done in a session of the House by one of its members in relation to the business before it.” Kilbourn v. Thompson, 103 U. S. 168, 204 (1881), quoted with approval in United States v. Johnson, 383 U. S., at 179. Rather than giving the Clause a cramped construction, the Court has sought to implement its fundamental purpose of freeing the legislator from executive and judicial oversight that realistically threatens to control his conduct as a legislator. We have little doubt that we are neither exceeding our judicial powers nor mistakenly construing the Constitution by holding that the Speech or Debate Clause applies not only to a Member but also to his aides insofar as the conduct of the latter would be a protected legislative act if performed by the Member himself.
  Nor can we agree with the United States that our conclusion is foreclosed by Kilbourn v. Thompson, supra, Dombrowski v. Eastland, 387 U. S. 82 (1967), and Powell v. McCormack, 395 U. S. 486 (1969), where the speech or debate privilege was held unavailable to certain House and committee employees. Those cases do not hold that persons other than Members of Congress are beyond the protection of the Clause when they perform or aid in the performance of legislative acts. In Kilbourn, the Speech or Debate Clause protected House Members who had adopted a resolution authorizing Kilbourn’s arrest; that act was clearly legislative in nature. But the resolution was subject to judicial review insofar as its execution impinged on a citizen’s rights as it did there. That the House could with impunity order an unconstitutional arrest afforded no protection for those who made the arrest. The Court quoted with approval from Stockdale v. Hansard, 9 Ad. & E. 1, 112 Eng. Rep. 1112 (K. B. 1839): “ 'So if the speaker by authority of the House order an illegal act, though that authority shall exempt him from question, his order shall no more justify the person who executed it than King Charles’s warrant for levying ship-money could justify his revenue officer/ ” 103 U. S., at 202. The Speech or Debate Clause could not be construed to immunize an illegal arrest even though directed by an immune legislative act. The Court was careful to point out that the Members themselves were not implicated in the actual arrest, id., at 200, and, significantly enough, reserved the question whether there might be circumstances in which “there may ... be things done, in the one House or the other, of an extraordinary character, for which the members who take part in the act may be held legally responsible.” 103 U. S., at 204 (emphasis added).
  Dombrowski v. Eastland, supra, is little different in principle. The Speech or Debate Clause there protected a Senator, who was also a subcommittee chairman, but not the subcommittee counsel. The record contained no evidence of the Senator’s involvement in any activity that could result in liability, 387 U. S., at 84, whereas the committee counsel was charged with conspiring with state officials to carry out an illegal seizure of records that the committee sought for its own proceedings. Ibid. The committee counsel was deemed protected to some extent by legislative privilege, but it did not shield him from answering as yet unproved charges of conspiring to violate the constitutional rights of private parties. Unlawful conduct of this kind the Speech or Debate Clause simply did not immunize.
  Powell v. McCormack reasserted judicial power to determine the validity of legislative actions impinging on individual rights — there the illegal exclusion of a representative-elect — and to afford relief against House aides seeking to implement the invalid resolutions. The Members themselves were dismissed from the case because shielded by the Speech or Debate Clause both from liability for their illegal legislative act and from having to defend themselves with respect to it. As in Kilbourn, the Court did not reach the question “whether under the Speech or Debate Clause petitioners would be entitled to maintain this action solely against the members of Congress where no agents participated in the challenged action and no other remedy was available.” 395 U. S., at 506 n. 26.
  None of these three cases adopted the simple proposition that immunity was unavailable to congressional or committee employees because they were not Representatives or Senators; rather, immunity was unavailable because they engaged in illegal conduct that was not entitled to Speech or Debate Clause protection. The three cases reflect a decidedly jaundiced view towards extending the Clause so as to privilege illegal or unconstitutional conduct beyond that essential to foreclose executive control of legislative speech or debate and associated matters such as voting and committee reports and proceedings. In Kilbourn, the Sergeant-at-Arms was executing a legislative order, the issuance of which fell within the Speech or Debate Clause; in Eastland, the committee counsel was gathering information for a hearing; and in Powell, the Clerk and Doorkeeper were merely carrying out directions that were protected by the Speech or Debate Clause. In each case, protecting the rights of others may have to some extent frustrated a planned or completed legislative act; but relief could be afforded without proof of a legislative act or the motives or purposes underlying such an act. No threat to legislative independence was posed, and Speech or Debate Clause protection did not attach.
  None of this, as we see it, involves distinguishing between a Senator and his personal aides with respect to legislative immunity. In Kilbourn-type situations, both aide and Member should be immune with respect to committee and House action leading to the illegal resolution. So, too, in Eastland, as in this litigation, senatorial aides should enjoy immunity for helping a Member conduct committee hearings. On the other hand, no prior case has held that Members of Congress would be immune if they executed an invalid resolution by themselves carrying out an illegal arrest, or if, in order to secure information for a hearing, themselves seized the property or invaded the privacy of a citizen. Neither they nor their aides should be immune from liability or questioning in such circumstances. Such acts are no more essential to legislating than the conduct held unprotected in United States v. Johnson, 383 U. S. 169 (1966).
  The United States fears the abuses that history reveals have occurred when legislators are invested with the power to relieve others from the operation of otherwise valid civil and criminal laws. But these abuses, it seems to us, are for the most part obviated if the privilege applicable to the aide is viewed, as it must be, as the privilege of the Senator, and invocable only by the Senator or by the aide on the Senator’s behalf, and if in all events the privilege available to the aide is confined to those services that would be immune legislative conduct if performed by the Senator himself. This view places beyond the Speech or Debate Clause a variety of services characteristically performed by aides for Members of Congress, even though within the scope of their employment. It likewise provides no protection for criminal conduct threatening the security of the person or property of others, whether performed at the direction of the Senator in preparation for or in execution of a legislative act or done without his knowledge or direction. Neither does it immunize Senator or aide from testifying at trials or grand jury proceedings involving third-party crimes where the questions do not require testimony about or impugn a legislative act. Thus our refusal to distinguish between Senator and aide in applying the Speech or Debate Clause does not mean that Rodberg is for all purposes exempt from grand jury questioning.
  II
  We are convinced also that the Court of Appeals correctly determined that Senator Gravel’s alleged arrangement with Beacon Press to publish the Pentagon Papers was not protected speech or debate within the meaning of Art. I, § 6, cl. 1, of the Constitution.
  Historically, the English legislative privilege was not viewed as protecting republication of an otherwise immune libel on the floor of the House. Stockdale v. Hansard, 9 Ad. & E., at 114, 112 Eng. Rep., at 1156, recognized that “[f]or speeches made in Parliament by a member to the prejudice of any other person, or hazardous to the public peace, that member enjoys complete impunity.” But it was clearly stated that “if the calumnious or inflammatory speeches should be reported and published, the law will attach responsibility on the publisher.” This was accepted in Kilbourn v. Thompson as a “sound statement of the legal effect of the Bill of Rights and of the parliamentary law of England” and as a reasonable basis for inferring “that the framers of the Constitution meant the same thing by the use of language borrowed from that source.” 103 U. S., at 202.
  Prior cases have read the Speech or Debate Clause “broadly to effectuate its purposes,” United States v. Johnson, 383 U. S., at 180, and have included within its reach anything “generally done in a session of the House by one of its members in relation to the business before it.” Kilbourn v. Thompson, 103 U. S., at 204; United States v. Johnson, 383 U. S., at 179. Thus, voting by Members and committee reports are protected; and we recognize today — as the Court has recognized before, Kilbourn v. Thompson, 103 U. S., at 204; Tenney v. Brandhove, 341 U. S. 367, 377-378 (1951) — that a Member’s conduct at legislative committee hearings, although subject to judicial review in various circumstances, as is legislation itself, may not be made the basis for a civil or criminal judgment against a Member because that conduct is within the “sphere of legitimate legislative activity.” Id., at 376.
  But the Clause has not been extended beyond the legislative sphere. That Senators generally perform certain acts in their official capacity as Senators does not necessarily make all such acts legislative in nature. Members of Congress are constantly in touch with the Executive Branch of the Government and with administrative agencies — they may cajole, and exhort with respect to the administration of a federal statute — but such conduct, though generally done, is not protected legislative activity. United States v. Johnson decided at least this much. “No argument is made, nor do we think that it could be successfully contended, that the Speech or Debate Clause reaches conduct, such as was involved in the attempt to influence the Department of Justice, that is in no wise related to the due functioning of the legislative process.” 383 U. S., at 172. Cf. Burton v. United States, 202 U. S., at 367-368.
  Legislative acts are not all-encompassing. The heart of the Clause is speech or debate in either House. Insofar as the Clause is construed to reach other matters, they must be an integral part of the deliberative and communicative processes by which Members participate in committee and House proceedings with respect to the consideration and passage or rejection of proposed legislation or with respect to other matters which the Constitution places within the jurisdiction of either House. As the Court of Appeals put it, the courts have extended the privilege to matters beyond pure speech or debate in either House, but “only when necessary to prevent indirect impairment of such deliberations.” United States v. Doe, 455 F. 2d, at 760.
  Here, private publication by Senator Gravel through the cooperation of Beacon Press was in no way essential to the deliberations of the Senate; nor does questioning as to private publication threaten the integrity or independence of the Senate by impermissibly' exposing its deliberations to executive influence. The Senator had conducted his hearings; the record and any report that was forthcoming were available both to his committee and the Senate. Insofar as we are advised, neither Congress nor the full committee ordered or authorized the publication. We cannot but conclude that the Senator’s arrangements with Beacon Press were not part and parcel of the legislative process.
  There are additional considerations. Article I, § 6, cl. 1, as we have emphasized, does not purport to confer a general exemption upon Members of Congress from liability or process in criminal cases. Quite the contrary is true. While the Speech or Debate Clause recognizes speech, voting, and other legislative acts as exempt from liability that might otherwise attach, it does not privilege either Senator or aide to violate an otherwise valid criminal law in preparing for or implementing legislative acts. If republication of these classified papers would be a crime under an Act of Congress, it would not be entitled to immunity under the Speech or Debate Clause. It also appears that the grand jury was pursuing this very subject in the normal course of a valid investigation. The Speech or Debate Clause does not in our view extend immunity to Rodberg, as a Senator’s aide, from testifying before the grand jury about the arrangement between Senator Gravel and Beacon Press or about his own participation, if any, in the alleged transaction, so long as legislative acts of the Senator are not impugned.
  HH I — I Í-H
  Similar considerations lead us to disagree with the Court of Appeals insofar as it fashioned, tentatively at least, a nonconstitutional testimonial privilege protecting Rodberg from any questioning by the grand jury concerning the matter of republication of the Pentagon Papers. This privilege, thought to be similar to that protecting executive officials from liability for libel, see Barr v. Matteo, 360 U. S. 564 (1959), was considered advisable “[t]o the extent that a congressman has responsibility to inform his constituents . . . 455 F. 2d, at 760. But we cannot carry a judicially fashioned privilege so far as to immunize criminal conduct proscribed by an Act of Congress or to frustrate the grand jury’s inquiry into whether publication of these classified documents violated a federal criminal statute. The so-called executive privilege has never been applied to shield executive officers from prosecution for crime, the Court of Appeals was quite sure that third parties were neither immune from liability nor from testifying about the republication matter, and we perceive no basis for conferring a testimonial privilege on Rodberg as the Court of Appeals seemed to do.
  IV
  We must finally consider, in the light of the foregoing, whether the protective order entered by the Court of Appeals is an appropriate regulation of the pending grand jury proceedings.
  Focusing first on paragraph two of the order, we think the injunction against interrogating Rodberg with respect to any act, “in the broadest sense,” performed by him within the scope of his employment, overly restricts the scope of grand jury inquiry. Rodberg’s immunity, testimonial or otherwise, extends only to legislative acts as to which the Senator himself would be immune. The grand jury, therefore, if relevant to its investigation into the possible violations of the criminal law, and absent Fifth Amendment objections, may require from Rodberg answers to questions relating to his or the Senator’s arrangements, if any, with respect to republication or with respect to third-party conduct under valid investigation by the grand jury, as long as the questions do not implicate legislative action of the Senator. Neither do we perceive any constitutional or other privilege that shields Rodberg, any more than any other witness, from grand jury questions relevant to tracing the source of obviously highly classified documents that came into the Senator’s possession and are the basic subject matter of inquiry in this case, as long as no legislative act is implicated by the questions.
  Because the Speech or Debate Clause privilege applies both to Senator and aide, it appears to us that paragraph one of the order, alone, would afford ample protection for the privilege if it forbade questioning any witness, including Rodberg: (1) concerning the Senator’s conduct, or the conduct of his aides, at the June 29, 1971, meeting of the subcommittee; (2) concerning the motives and purposes behind the Senator’s conduct, or that of his aides, at that meeting; (3) concerning communications between the Senator and his aides during the term of their employment and related to said meeting or any other legislative act of the Senator; (4) except as it proves relevant to investigating possible third-party crime, concerning any act, in itself not criminal, performed by the Senator, or by his aides in the course of their employment, in preparation for the subcommittee hearing. We leave the final form of such an order to the Court of Appeals in the first instance, or, if that court prefers, to the District Court.
  The judgment of the Court of Appeals is vacated and the cases are remanded to that court for further proceedings consistent with this opinion.
  So ordered.
  The District Court permitted Senator Gravel to intervene in the proceeding on Dr. Rodberg’s motion to quash the subpoena ordering his appearance before the grand jury and accepted motions from Gravel to quash the subpoena and to specify the exact nature of the questions to be asked Rodberg. The Government contested Gravel’s standing to appeal the trial court’s disposition of these motions on the ground that, had the subpoena been directed to the Senator, he could not have appealed from a denial of a motion to quash without first refusing to comply with the subpoena and being held in contempt. United States v. Ryan, 402 U. S. 530 (1971); Cobbledick v. United States, 309 U. S. 323 (1940). The Court of Appeals, United States v. Doe, 455 F. 2d 753, 756-757 (CA1 1972), held that because the subpoena was directed to third parties, who could not be counted on to risk contempt to protect intervenor’s rights, Gravel might be “powerless to avert the mischief of the order” if not permitted to appeal, citing Perlman v. United States, 247 U. S. 7, 13 (1918). The United States does not here challenge the propriety of the appeal.
  Dr. Rodberg, who filed his own motion to quash the subpoena directing his appearance and testimony, appeared as amicus curiae both in the Court of Appeals and this Court. Technically, Rodberg states, he is a party to No. 71-1026, insofar as the Government appeals from the protective order entered by the District Court. However, since Gravel intervened, Rodberg does not press the point. Brief of Leonard S. Rodberg as Amicus Curiae 2 n. 2.
  The District Court found “that 'as personal assistant to movant [Gravel], Dr. Rodberg assisted movant in preparing for disclosure and subsequently disclosing to movant’s colleagues and constituents, at a hearing of the Senate Subcommittee on Public Buildings and Grounds, the contents of the so-called “Pentagon Papers,” which were critical of the Executive’s conduct in the field of foreign relations.’ ” United States v. Doe, 332 F. Supp. 930, 932 (Mass. 1971).
  Beacon Press is a division of the Unitarian Universalist Association, which appeared here as amicus curiae in support of the position taken by Senator Gravel.
  Gravel so alleged in his motion to intervene in the Webber matter and to quash the subpoena ordering Webber to appear and testify. App. 15-18.
  The Government maintained that Congress does not enjoy unlimited power to conduct business and that judicial review has often been exercised to curb extra-legislative incursions by legislative committees, citing Watkins v. United States, 354 U. S. 178 (1957); McGrain v. Daugherty, 273 U. S. 135 (1927); Hentoff v. Ichord, 318 F. Supp. 1175 (DC 1970), at least where such incursions are unrelated to a legitimate legislative purpose. It was alleged that Gravel had “convened a special, unauthorized, and untimely meeting of the Senate Subcommittee on Public Works (at midnight on June 29, 1971), for the purpose of reading the documents and thereafter placed all unread portions in the subcommittee record, with Dr. Rodberg soliciting publication following the meeting.” App. 9. The District Court rejected the contention: “Senator Gravel has suggested that the availability of funds for the construction and improvement of public buildings and grounds has been affected by the necessary costs of the war in Vietnam and that therefore the development and conduct of the war is properly within the concern of his subcommittee. The court rejects the Government’s argument without detailed consideration of the merits of the Senator’s position, on the basis of the general rule restricting judicial inquiry into matters of legislative purpose and operations.” United States v. Doe, 332 F. Supp., at 935. Cases such as Watkins, supra, were distinguished on the ground that they concerned the power of Congress under the Constitution: “It has not been suggested by the Government that the Subcommittee itself is unauthorized, nor that the war in Vietnam is an issue beyond the purview of congressional debate and action. Also, the individual rights at stake in these proceedings are not those of a witness before a congressional committee or of a subject of a committee’s investigation, but only those of a congressman and member of his personal staff who claim ‘intimidation by the executive.’ ” 332 F. Supp., at 936.
  The District Court thought that Rodberg could be questioned concerning his own conduct prior to joining the Senator’s staff and concerning the activities of third parties with whom Rodberg and Gravel dealt. Id., at 934.
  The protective order entered by the District Court provided as follows:
  “(1) No witness before the grand jury currently investigating the release of the Pentagon Papers may be questioned about Senator Mike Gravel’s conduct at a meeting of the Subcommittee on Public Buildings and Grounds on June 29, 1971 nor about things done by the Senator in preparation for and intimately related to said meeting.
  “(2) Dr. Leonard S. Rodberg may not be questioned about his own actions on June 29, 1971 after having been engaged as a member of Senator Gravel’s personal staff to the extent that they were taken at the Senator’s direction either at a meeting of the Subcommittee on Public Buildings and Grounds or in preparation for and intimately related to said meeting.” Id., at 938.
  The Court of Appeals thought third parties could be questioned as to their own conduct regarding the Pentagon Papers, “including their dealing with intervenor or his aides.” United States v. Doe, 455 F. 2d, at 761. The court found no merit in the claim that such parties should be shielded from questioning under the Speech or Debate Clause concerning their own wrongful acts, even if such questioning may bring the Senator’s conduct into question. Id., at 758 n. 2.
  Williamson, United States Congressman, had been found guilty of conspiring to commit subornation of perjury in connection with proceedings for the purchase of public land. He objected to the court’s passing sentence upon him and particularly protested that any imprisonment would deprive him of his constitutional right to “go to, attend at and return from the ensuing session of Congress.” Williamson v. United States, 207 U. S. 425, 433 (1908). The Court rejected the contention that the Speech or Debate Clause freed legislators from accountability for criminal conduct.
  In Kilbourn v. Thompson, 103 U. S. 168, 198 (1881), the Court noted a second example, used by Mr. Justice Coleridge in Stockdale v. Hansard, 9 Ad. & E. 1, 225-226, 112 Eng. Rep. 1112, 1196-1197 (K. B. 1839): “ 'Let me suppose, by way of illustration, an extreme case; the House of Commons resolves that any one wearing a dress of a particular manufacture is guilty of a breach of privilege, and orders the arrest of such persons by the constable of the parish. An arrest is made and action brought, to which the order of the House is pleaded as a justification. ... In such a case as the one supposed, the plaintiff’s counsel would insist on the distinction between power and privilege; and no lawyer can seriously doubt that it exists: but the argument confounds them, and forbids us to enquire, in any particular case, whether it ranges under the one or the other. I can find no principle which sanctions this.’ ”
  Senator Gravel is willing to assume that if he personally had “stolen” the Pentagon Papers, and that act were a crime, he could be prosecuted, as could aides or other assistants who participated in the theft. Consolidated Brief for Senator Gravel 93.
  It follows that an aide’s claim of privilege can be repudiated and thus waived by the Senator.
  Stockdale extensively reviewed the precedents and their interplay with the privilege so forcefully recognized in the Bill of Rights of 1689: “That the Freedom of Speech, and Debates or Proceedings in Parliament, ought not to be impeached or questioned in any Court or Place out of Parliament.” 1 W. & M., Sess. 2, c. 2. From these cases, including Rex v. Creevey, 1 M. & S. 273, 105 Eng. Rep. 102 (K. B. 1813); Rex v. Wright, 8 T. R. 293, 101 Eng. Rep. 1396 (K. B. 1799); Rex v. Abingdon, 1 Esp. 226,170 Eng. Rep. 337 (N. P. 1794); Rex v. Williams, 2 Show. K. B. 471, 89 Eng. Rep. 1048 (1686), it is apparent that to the extent English precedent is relevant to the Speech or Debate Clause there is little, if any, support for Senator Gravel’s position with respect to republication. Parliament reacted to Stockdale v. Hansard by adopting the Parliamentary Papers Act of 1840, 3 & 4 Viet., c. 9, which stayed proceedings in all cases where it could be shown that publication was by order of a House of Parliament and was a bona fide report, printed and circulated without malice. See generally C. Wittke, The History of English Parliamentary Privilege (1921).
  Gravel urges that Stockdale v. Hansard was later repudiated in Wason v. Walter, L. R. 4 Q. B. 73 (1868), which held a proprietor immune from civil libel for an accurate republication of a debate in the House of Lords. But the immunity established in Wason was not founded on parliamentary privilege, id., at 84, but upon analogy to the privilege for reporting judicial proceedings. Id., at 87-90. The Wason court stated its “unhesitating and unqualified adhesion” to the “masterly judgments” rendered in Stockdale and characterized the question before it as whether republication, quite apart from any assertion of parliamentary privilege, was “in itself privileged and lawful.” Id., at 86-87. That the privileges for nonmalicious republication of parliamentary and judicial proceedings — later established as qualified — were construed as coextensive in all respects, id., at 95, further underscores the inappositeness of reading Wason as based upon parliamentary privilege that, like the Speech or Debate Clause, is absolute. Much later Holdsworth was to comment that at the time of Wason the distinction between absolute and qualified privilege had not been worked out and that the “part played by malice in the tort and crime of defamation” probably helped retard recognition of a qualified privilege. 8 W. Holdsworth, History of English Law 377 (1926).
  The Court in Tenney v. Brandhove, 341 U. S. 367, 376-377 (1951), was equally clear that “legislative activity” is not all-encompassing, nor may its limits be established by the Legislative Branch: “Legislatures may not of course acquire power by an unwarranted extension of privilege. The House of Commons’ claim of power to establish the limits of its privilege has been little more than a pretense since Ashby v. White, 2 Ld. Raym. 938, 3 id. 320. This Court has not hesitated to sustain the rights of private individuals when it found Congress was acting outside its legislative role. Kilbourn v. Thompson, 103 U. S. 168; Marshall v. Gordon, 243 U. S. 521; compare McGrain v. Daugherty, 273 U. S. 135, 176.”
  The sole constitutional claim asserted here is based on the Speech or Debate Clause. We need not address issues that may arise when Congress or either House, as distinguished from a single Member, orders the publication and/or public distribution of committee hearings, reports, or .other materials. Of course, Art. I, § 5, cl. 3, requires that each House “keep a Journal of its Proceedings, and from time to time publish the same, excepting such Parts as may in their Judgment require Secrecy . . . .” This Clause has not been the subject of extensive judicial examination. See Field v. Clark, 143 U. S. 649, 670-671 (1892); United States v. Ballin, 144 U. S. 1, 4 (1892).
  The Court of Appeals held that the Speech or Debate Clause protects aides as well as Senators and that while third parties maybe questioned about the source of a Senator’s information, neither aide nor Senator need answer such inquiries. The Government’s position is that the aide has no protection under the Speech or Debate Clause and may be questioned even about legislative acts. A contrary ruling, the Government fears, would invite great abuse. On the other hand, Gravel contends that the Court of Appeals insufficiently protected the Senator both with respect to the matter of republication and with respect to the scope of inquiry permitted the grand jury in questioning third-party witnesses with whom the Senator and his aides dealt. Hence, we are of the view that both the question of the aide’s immunity and the question of the extent of that immunity are properly before us in this case. And surely we are not bound by the Government’s view of the scope of the privilege.
  Having established that neither the Senator nor Rodberg is subject to liability for what occurred at the subcommittee hearing, we perceive no basis for inquiry of either Rodberg or third parties on this subject. If it proves material to establish for the record the fact of publication at the subcommittee hearing, which seems undisputed, the public record of the hearing would appear sufficient for this purpose. We do not intend to imply, however, that in no grand jury investigations or criminal trials of third parties may third-party witnesses be interrogated about legislative acts of Members of Congress. As for inquiry of Rodberg about third-party crimes, we are quite sure that the District Court has ample power to keep the grand jury proceedings within proper bounds and to foreclose improvident harassment and fishing expeditions into the affairs of a Member of Congress that are no proper concern of the grand jury or the Executive Branch.