dissenting in part.
The Court today holds that the Speech or Debate Clause does not protect a Congressman from being forced to testify before a grand jury about sources of information *630used in preparation for legislative acts. This critical question was not embraced in the petitions for certiorari. It was not dealt with in the written briefs. It was addressed only tangentially during the oral arguments. Yet it is a question with profound implications for the effective functioning of the legislative process. I cannot join in the Court’s summary resolution of so vitally important a constitutional issue.
In preparing for legislative hearings, debates, and roll calls, a member of Congress obviously needs the broadest possible range of information. Valuable information may often come from sources in the Executive Branch or from citizens in private life. And informants such as these may be willing to relate information to a Congressman only in confidence, fearing that disclosure of their identities might cause loss of their jobs or harassment by their colleagues or employers. In fact, I should suppose it to be self-evident that many such informants would insist upon an assurance of confidentiality before revealing their information. Thus, the acquisition of knowledge through a promise of nondisclosure of its source will often be a necessary concomitant of effective legislative conduct, if the members of Congress are properly to perform their constitutional duty.
The Court of Appeals for the First Circuit recognized the importance of the information-gathering process in the performance of the legislative function. It held that the Speech or Debate Clause bars all grand jury questioning of a member of Congress regarding the sources of his information. The Court of Appeals reasoned that to allow a “grand jury to question a senator about his sources would chill both the vigor with which legislators seek facts, and the willingness of potential sources to supply them.” United States v. Doe, 455 F. 2d 753, 758-759. The Government did not seek review of this ruling, but rather sought certiorari on the question whether the *631Speech or Debate Clause bars a grand jury from questioning congressional aides about privileged actions of Senators or Representatives.1
The Court, however, today decides, sua sponte, that a Member of Congress may, despite the Speech or Debate Clause, be compelled to testify before a grand jury concerning the sources of information used by him in the performance of his legislative duties, if such an inquiry “proves relevant to investigating possible third-party crime.” Ante, at 629 (emphasis supplied).2 In my view, this ruling is highly dubious-in view of the basic purpose of the Speech or Debate Clause — “to prevent intimidation {of Congressmen] by the executive and accountability before a possibly hostile judiciary.” United States v. Johnson, 383 U. S. 169, 181.
Under the Court’s ruling, a Congressman may be subpoenaed by a vindictive Executive to testify about informants who have not committed crimes and who have no knowledge of crime. Such compulsion can occur, because the judiciary has traditionally imposed virtually no limitations on the grand jury’s broad investigatory powers; grand jury investigations are not limited in scope *632to specific criminal acts, and standards of materiality and relevance are greatly relaxed.3 But even if the Executive had reason to believe that a Member of Congress had knowledge of a specific probable violation of law, it is by no means clear to me that the Executive’s interest in the administration of justice must always override the public interest in having an informed Congress. Why should we not, given the tension between two competing interests, each of constitutional dimensions, balance the claims of the Speech or Debate Clause against the claims of the grand jury in the particularized contexts of specific cases? And why are not the Houses of Congress the proper institutions in most situations to impose sanctions upon a Representative or Senator who withholds information about crime acquired in the course of his legislative duties?4
*633I am not prepared to accept the Court’s rigid conclusion that the Executive may always compel a legislator to testify before a grand jury about sources of information used in preparing for legislative acts. For that reason, I dissent from that part of the Court’s opinion that so inflexibly and summarily decides this vital question.
As stated in its petition for certiorari, the Government asked us to consider:
“Whether Article 1, Section 6, of the Constitution providing that ‘. . . for any Speech or Debate in either House,’ the Senators and Representatives ‘shall not be questioned in any other Place’ bars a grand jury from questioning aides of members of Congress and other persons about matters that may touch on activities of a member of Congress which are protected ‘Speech or Debate.’ ”
The Government also asked us to consider:
“Whether an aide of a member of Congress has a common law privilege not to testify before a grand jury concerning private republication of material which his Senator-employer had introduced into the record of a Senate subcommittee.”
We granted certiorari on both questions. 405 U. S. 916.
See also ante, at 622, 628.
See, e. g., Wilson v. United States, 221 U. S. 361; Hendricks v. United States, 223 U. S. 178; United States v. Johnson, 319 U. S. 503. See generally Holt v. United States, 218 U. S. 245; Costello v. United States, 350 U. S. 359.
During oral argument, the Solicitor General virtually conceded, in the course of arguing that aides should not enjoy the same testimonial privilege as Congressmen, that a Senator could not be called before the grand jury to testify about the sources of his information:
“Q. Mr. Solicitor, am I correct that you wouldn’t be able to question the Senator as to where he got the papers from?
“A. Oh, Mr. Justice, we are not able to question the Senator about anything insofar as it relates to speech or debate.
“Q. Well, this was related, you agree, to speech and debate?
“A. I am not contending to the contrary. . . .” Tr. of Oral Arg., Apr - 20, 1972, pp. 27-28.
The following exchange also took place:
“Q. You can’t ask a Senator where you got the material you used in your speech.
“A. Yes, Mr. Justice.
“Q. You can’t.
“A. Yes.” Id., at 29.
At another point in the oral argument, the Solicitor General said *633that even when a Senator or Representative has knowledge of crime as a result of legislative acts “[t]hey can’t even be required to respond to questions with respect to their speeches and debates. That is a great and historic privilege which ought to be maintained which I fully support but which does not extend to any other persons than Senators and Representatives.” Id., at 32.