Mr. Justice Frankfurter
delivered the opinion of the Court.
On November 10, 1954, the United States Attorney for the Southern District of New York filed an application under the Immunity Act of 1954, 68 Stat. 745, 18 U. S. C. (Supp. II) § 3486, for an order requiring petitioner to testify before a grand jury. The Immunity Act, in its pertinent portions, provides:
“(c) Whenever in the judgment of a United States attorney the testimony of any witness, or the production of books, papers, or other evidence by any witness, in any case or proceeding before any grand jury or court of the United States involving any interference with or endangering of, or any plans or attempts to interfere with or endanger, the national security or defense of the United States by treason, sabotage, espionage, sedition, seditious conspiracy, violations of chapter 115 of title 18 of the United States Code, violations of the Internal Security Act of 1950 (64 Stat. 987), violations of the Atomic Energy Act of 1946 (60 Stat. 755), as amended, violations of sections 212 (a) (27), (28), (29) or 241 (a)(6), (7) or 313 (a) of the Immigration and Nationality Act (66 Stat. 182-186; 204-206; 240-241), and conspiracies involving any of the foregoing, is necessary to the public interest, he, upon the approval of the Attorney General, shall make application to the court that the witness shall be instructed to testify or produce evidence subject to the provisions of this section, and upon order of the court such witness shall not be excused from testifying or from producing books, papers, or other evidence on the ground that the testimony or evidence required of him may tend to incriminate him or subject him to a penalty or forfeiture. But no such witness shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter, or thing concerning which he is compelled, after having claimed his privilege against self-incrimination, to testify or produce evidence, nor shall testimony so compelled be used as evidence in any criminal proceeding (except prosecution described in subsection (d) hereof) against him in any court.
“(d) No witness shall be exempt under the provision of this section from prosecution for perjury or contempt committed while giving testimony or producing evidence under compulsion as provided in this section.”
In his application the United States Attorney alleged the following facts. On November 3, 1954, petitioner, pursuant to subpoena, appeared before a duly constituted grand jury of the Southern District of New York which was investigating matters concerned with attempts to endanger the national security by espionage and conspiracy to commit espionage. The grand jury asked him a series of questions relating to his knowledge of such activities, to his and other persons’ participation in such activities, and to his and other persons’ membership in the Communist Party. Petitioner, invoking the privilege against self-incrimination, refused to answer the questions. The United States Attorney also asserted that he deemed the testimony necessary to the public interest of the United States, and annexed a letter from the Attorney General of the United States approving the application. The United States Attorney, in compliance with a request of the district judge, filed an affidavit asserting his own good faith in filing the application.
Petitioner, contesting the application, attacked the constitutionality of the Act and urged that, if the immunity statute be held constitutional, the District Court should, in the exercise of its discretion, deny the application. He filed an affidavit setting forth in detail experiences with agents of the Department of Justice and congressional investigating committees and other information in support of his plea for an exercise of discretion by the District Court. The Government in reply filed affidavits denying some of the allegations set forth in petitioner’s affidavit.
On January 31, 1955, the District Court sustained the constitutionality of the statute. 128 F. Supp. 617. Its order, dated February 8, 1955, instructed petitioner “to answer the questions propounded to him before the Grand Jury and to testify and produce evidence with respect to such matters under inquiry before said Grand Jury . . . .” Petitioner appealed from this order, but the Court of Appeals for the Second Circuit dismissed the appeal on the authority of Cobbledick v. United States, 309 U. S. 323.
Petitioner again refused to answer the questions which the District Court had ordered him to answer. He was then brought before the District Court and, on stipulation that he had refused to obey the order of the court of February 8, he was convicted of contempt and sentenced to six months’ imprisonment unless he should purge himself of the contempt. Petitioner appealed to the Court of Appeals for the Second Circuit which affirmed the judgment of the District Court. 221 F. 2d 760. The importance of the questions at issue, in view of the differences between the legislation sustained in Brown v. Walker, 161 U. S. 591, and the Act under review, led us to bring the case here. 349 U. S. 951.
Four major questions are raised by this appeal: Is the immunity provided by the Act sufficiently broad to displace the protection afforded by the privilege against self-in crimination? Assuming that the statutory requirements are met, does the Act give the district judge discretion to deny an application for an order requiring a witness to answer relevant questions put by the grand jury, and, if so, is the court thereby required to exercise a function that is not an exercise of “judicial Power”? Did Congress provide immunity from state prosecution for crime, and, if so, is it empowered to do so? Does the Fifth Amendment prohibit compulsion of what would otherwise be self-incriminating testimony no matter what the scope of the immunity statute?
It is relevant to define explicitly the spirit in which the Fifth Amendment’s privilege against self-incrimination should be approached. This command of the Fifth Amendment (“nor shall any person ... be compelled in any criminal case to be a witness against himself . . . .”) registers an important advance in the development of our liberty — “one of the great landmarks in man’s struggle to make himself civilized.” Time has not shown that protection from the evils against which this safeguard was directed is needless or unwarranted. This constitutional protection must not be interpreted in a hostile or niggardly spirit. Too many, even those who should be better advised, view this privilege as a shelter for wrongdoers. They too readily assume that those who invoke it are either guilty of crime or commit perjury in claiming the privilege. Such a view does scant honor to the patriots who sponsored the Bill of Rights as a condition to acceptance of the Constitution by the ratifying States. The Founders of the Nation were not naive or disregardful of the interests of justice. The difference between them and those who deem the privilege an obstruction to due inquiry has been appropriately indicated by Chief Judge Magruder:
“Our forefathers, when they wrote this provision into the Fifth Amendment of the Constitution, had in mind a lot of history which has been largely forgotten to-day. See VIII Wigmore on Evidence (3d ed. 1940) § 2250 et seq.; Morgan, The Privilege Against Self-Incrimination, 34 Minn. L. Rev. 1 (1949). They made a judgment and expressed it in our fundamental law, that it were better for an occasional crime to go unpunished than that the prosecution should be free to build up a criminal case, in whole or in part, with the assistance of enforced disclosures by the accused. The privilege against self-incrimination serves as a protection to the innocent as well as to the guilty, and we have been admonished that it should be given a liberal application. Hoffman v. United States, . . . 341 U. S. 479, 486 .... If it be thought that the privilege is outmoded in the conditions of this modern age, then the thing to do is to take it out of the Constitution, not to whittle it down by the subtle encroachments of judicial opinion.” Maffie v. United States, 209 F. 2d 225, 227.
Nothing new can be put into the Constitution except through the amendatory process. Nothing old can be taken out without the same process.
No doubt the constitutional privilege may, on occasion, save a guilty man from his just deserts. It was aimed at a more far-reaching evil — a recurrence of the Inquisition and the Star Chamber, even if not in their stark brutality. Prevention of the greater evil was deemed of more importance than occurrence of the lesser evil. Having had much experience with a tendency in human nature to abuse power, the Founders sought to close the doors against like future abuses by law-enforcing agencies.
As no constitutional guarantee enjoys preference, so none should suffer subordination or deletion. It is appropriate to read the conviction expressed in a memorable address by Senator Albert J. Beveridge to the American Bar Association in 1920, a time when there was also manifested impatience with some of the restrictions of the Constitution in the presumed interest of security. His appeal was to the Constitution — to the whole Constitution, not to a mutilating selection of those parts only which for the moment find favor. To view a particular provision of the Bill of Rights with disfavor inevitably results in a constricted application of it. This is to disrespect the Constitution.
It is in this spirit of strict, not lax, observance of the constitutional protection of the individual that we approach the claims made by petitioner in this case. The attack on the Immunity Act as violating the Fifth Amendment is not a new one. Sixty years ago this Court considered, in Brown v. Walker, 161 U. S. 591, the constitutionality of a similar Act, the Act of February 11, 1893, 27 Stat. 443. In that case, Brown, auditor for a railroad company, had been subpoenaed to testify before a grand jury which was investigating charges that officers and agents of the company had violated the Interstate Commerce Act. Invoking the privilege against self-incrimination, he refused to answer certain questions concerning the operations and the rebate policy of the railroad. On an order to show cause before the United States District Court for the Western District of Pennsylvania, he was adjudged in contempt. His petition for a writ of habeas corpus to the Circuit Court for the Western District of Pennsylvania was dismissed. Petitioner appealed to this Court, urging that the 1893 immunity statute was unconstitutional.
The Court considered and rejected petitioner’s arguments, holding that a statute which compelled testimony but secured the witness against a criminal prosecution which might be aided directly or indirectly by his disclosures did not violate the Fifth Amendment’s privilege against self-incrimination and that the 1893 statute did provide such immunity. “While the constitutional provision in question is justly regarded as one of the most valuable prerogatives of the citizen, its object is fully accomplished by the statutory immunity, and we are, therefore, of opinion that the witness was compellable to answer . . . .” 161 U. S., at 610.
Petitioner, however, attempts to distinguish Brown v. Walker. He argues that this case is different from Brown v. Walker because the impact of the disabilities imposed by federal and state authorities and the public in general — such as loss of job, expulsion from labor unions, state registration and investigation statutes, passport eligibility, and general public opprobrium — is so oppressive that the statute does not give him true immunity. This, he alleges, is significantly different from the impact of testifying on the auditor in Brown v. Walker, who could the next day resume his job with reputation unaffected. But, as this Court has often held, the immunity granted need only remove those sanctions which generate the fear justifying invocation of the privilege: “The interdiction of the Fifth Amendment operates only where a witness is asked to incriminate himself — in other words, to give testimony which may possibly expose him to a criminal charge. But if the criminality has already been taken away, the Amendment ceases to apply.” Hale v. Henkel, 201 U. S. 43, 67. Here, since the Immunity Act protects a witness who is compelled to answer to the extent of his constitutional immunity, he has of course, when a particular sanction is sought to be imposed against him, the right to claim that it is criminal in nature.
Again, the petitioner seeks to distinguish this case from Brown v. Walker by claiming that under the Immunity Act of 1954 the district judge to whom the United States Attorney must apply for an order instructing him to testify has discretion in granting the order and thus has discretion in granting the immunity which automatically follows from the order. Petitioner cites the language of the statute, the legislative history, and miscellaneous other authorities in support of his construction. The Government contends that the court has no discretion to determine whether the public interest would best be served by exchanging immunity from prosecution for testimony, that its only function is to order a witness to testify if it determines that the case is within the framework of the statute.
We are concerned here only with § (c) and therefore need not pass on this question with respect to §§ (a) and (b) of the Act. A fair reading of § (c) does not indicate that the district judge has any discretion to deny the order on the ground that the public interest does not warrant it. We agree with District Judge Weinfeld’s interpretation of this section:
“The most that can be said for the legislative history is that it is on the whole inconclusive. Certainly, it contains nothing that requires the court to reject the construction which the statutory language clearly requires. Especially is this so where the construction contended for purports to raise a serious constitutional question as to the role of the judiciary under the doctrine of separation of powers. The Supreme Court has repeatedly warned ‘if a serious doubt of constitutionality is raised, it is a cardinal principle that this Court will first ascertain whether a construction of the statute is fairly possible by which the question may be avoided.’ Indeed, the Court has stated that words may be strained ‘in the candid service of avoiding a serious constitutional doubt.’ Here there is no need to strain words. It requires neither torturing of language nor disregard of a clear legislative policy to avoid the constitutional question advanced by the witness. Indeed, to reach the constitutional issue would require straining of language. In such circumstances the court’s duty is plainly to avoid the constitutional question.” 128 F. Supp., at 627-628.
Since the Court’s duty under § (c) is only to ascertain whether the statutory requirements are complied with by the grand jury, the United States Attorney, and the Attorney General, we have no difficulty in concluding that the district court is confined within the scope of “judicial Power.” Interstate Commerce Commission v. Brimson, 154 U. S. 447.
Petitioner further argues that the immunity is not constitutionally sufficient so long as a witness is subject to the very real possibility of state prosecution. He urges that the statute does not, and constitutionally could not, grant such immunity. The immunity portion of the statute contains two parts. The first prohibits prosecutions and is worded virtually in the terms of the 1893 Act. The second makes explicit that the compelled testimony shall not be used against the witness in any proceeding in any court. Such a clause was construed in Adams v. Maryland, 347 U. S. 179, to apply to state courts. In Brown v. Walker, it was urged that the prohibition against prosecution did not grant protection against prosecution in the state courts. First finding that Congress could constitutionally provide such immunity, the Court then interpreted the statute:
“The act in question contains no suggestion that it is to be applied only to the Federal courts. It declares broadly that ‘no person shall be excused from attending and testifying . . . before the Interstate Commerce Commission ... on the ground . . . that the testimony . . . required of him may tend to criminate him,’ etc. ‘But no person shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter or thing concerning which he may testify,’ etc. It is not that he shall not be prosecuted for or on account of any crime concerning which he may testify, which might possibly be urged to apply only to crimes under the Federal law and not to crimes, such as the passing of counterfeit money, etc., which are also cognizable under state laws; but the immunity extends to any transaction, matter or thing concerning which he may testify, which clearly indicates that the immunity is intended to be general, and to be applicable whenever and in whatever court such prosecution may be had.” 161 U. S., at 607-608.
The Report of the Committee on the Judiciary of the House of Representatives supports the broad interpretation of the Act before us:
“Even though the power of Congress to prohibit a subsequent State prosecution is doubtful, such a constitutional question should not prevent the enactment of the recommended bill. The language of the amendment ... is sufficiently broad to ban a subsequent State prosecution if it be determined that the Congress has the constitutional power to do so. In addition, the amendment recommended provides the additional protection — as set forth in the Adams case, by outlawing the subsequent use of the compelled testimony in any criminal proceeding — State or Federal.
“By the use of these two distinct concepts, the committee believes that the fullest protection that can be afforded the witness will be achieved.” H. R. Rep. No. 2606, 83d Cong., 2d Sess. 7.
Petitioner questions the constitutional power of Congress to grant immunity from state prosecution. Congressional abolition of state power to punish crimes committed in violation of state law presents a more drastic exercise of congressional power than that which we considered in Adams. In that case, only the use of the compelled testimony, not prosecution itself, was prohibited. Here the State is forbidden to prosecute. But it cannot be contested that Congress has power to provide for national defense and the complementary power "To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof.” U. S. Const., Art. I, § 8, cl. 18. The Immunity Act is concerned with the national security. It reflects a congressional policy to increase the possibility of more complete and open disclosure by removal of fear of state prosecution. We cannot say that Congress’ paramount authority in safeguarding national security does not justify the restriction it has placed on the exercise of state power for the more effective exercise of conceded federal power. We have already, in the name of the Commerce Clause, upheld a similar restriction on state court jurisdiction, Brown v. Walker, 161 U. S., at 606-607, and we can find no distinction between the reach of congressional power with respect to commerce and its power with respect to national security. See also Hines v. Davidowitz, 312 U. S. 52.
Petitioner also urges that if Brown v. Walker is found nondistinguishable and controlling, then that case should be reconsidered and overruled. He also urges upon us a “return” to a literal reading of the Fifth Amendment. Brown v. Walker was the second case to deal with an immunity statute. Four years previously, in Counselman v. Hitchcock, 142 U. S. 547, a unanimous Court had found constitutionally inadequate the predecessor to the 1893 statute because the immunity granted was incomplete, in that it merely forbade the use of the testimony given and failed to protect a witness from future prosecution based on knowledge and sources of information obtained from the compelled testimony. It was with this background that the 1893 statute, providing complete immunity from prosecution, was passed and that Brown v. Walker was argued and decided. As in Counselman, appellant’s numerous arguments were presented by James C. Carter, widely acknowledged as the leader of the American bar. The Court was closely divided in upholding the statute, and the opinions reflect the thoroughness with which the issues were considered. Since that time the Court’s holding in Brown v. Walker has never been challenged; the case and the doctrine it announced have consistently and without question been treated as definitive by this Court, in opinions written, among others, by Holmes and Brandeis, JJ. See, e. g., McCarthy v. Arndstein, 266 U. S. 34, 42; Heike v. United States, 227 U. S. 131,142. The 1893 statute has become part of our constitutional fabric and has been included “in substantially the same terms, in virtually all of the major regulatory enactments of the Federal Government.” Shapiro v. United States, 335 U. S. 1, 6. For a partial list of these statutes, see, id., at 6-7, n. 4. Moreover, the States, with one exception — a case decided prior to Brown v. Walker — have, under their own constitutions, enunciated the same doctrine, 8 Wigmore, Evidence (3d ed.), § 2281, and have passed numerous statutes compelling testimony in exchange for immunity in the form either of complete amnesty or of prohibition of the use of the compelled testimony. For a list of such statutes, see 8 Wigmore, Evidence (3d ed.), § 2281, n. 11 (pp. 478-501) and Pocket Supplement thereto, § 2281, n. 11 (pp. 147-157).
We are not dealing here with one of the vague, undefinable, admonitory provisions of the Constitution whose scope is inevitably addressed to changing circumstances. The privilege against self-incrimination is a specific provision of which it is peculiarly true that “a page of history is worth a volume of logic.” New York Trust Co. v. Eisner, 256 U. S. 345, 349. For the history of the privilege establishes not only that it is not to be interpreted literally, but also that its sole concern is, as its name indicates, with the danger to a witness forced to give testimony leading to the infliction of “penalties affixed to the criminal acts . . . .” Boyd v. United States, 116 U. S. 616, 634. We leave Boyd v. United States unqualified, as it was left unqualified in Brown v. Walker. Immunity displaces the danger. Once the reason for the privilege ceases, the privilege ceases. We reaffirm Brown v. Walker, and in so doing we need not repeat the answers given by that case to the other points raised by petitioner.
The judgment of the Court of Appeals is
Affirmed.
Griswold, The Fifth Amendment Today (1955), 7.
Father John Fearon, O. P., has addressed himself to this misapprehension: “What is to be said of the opinion that an innocent man has an obligation in conscience not to have recourse to the Fifth Amendment? Since the natural law does not provide explicitly for this circumstance moral obligation has to be determined by civil law. Actually the determination of civil law is quite clear: the innocent and guilty alike have a right of recourse to the Fifth Amendment. And if the innocent man has.a clearly defined right to such recourse it is inconceivable that he could simultaneously have a duty not to have recourse, since rights and duties are correlative. Nor can it be urged that non-recourse is a duty of piety rather than justice. If such an opinion were binding and all innocent men waived their rights to the protection of the Fifth Amendment, the purpose of the law would be defeated and the common welfare of the nation would suffer rather than prosper.” Congressional Investigations and Moral Theology, The Commonweal, Feb. 19, 1954, 497, 499.
“If liberty is worth keeping and free representative government worth saving, we must stand for all American fundamentals — not some, but all. All are woven into the great fabric of our national well-being. We cannot hold fast to some only, and abandon others that, for the moment, we find inconvenient. If one American fundamental is prostrated, others in the end will surely fall. The success or failure of the American theory of society and government, depends upon our fidelity to every one of those inter-dependent parts of that immortal charter of orderly freedom, the Constitution of the United States.” Beveridge, The Assault upon American Fundamentals, 45 Reports of American Bar Assn., 188, 216 (1920).
“. . . no person shall be excused from attending and testifying or from producing books, papers, tariffs, contracts, agreements and documents before the Interstate Commerce Commission, or in obedience to the subpoena of the Commission ... or in any cause or proceeding, criminal or otherwise, based upon or growing out of any alleged violation of the act of Congress, entitled, ‘An act to regulate commerce,’ ... on the ground or for the reason that the testimony or evidence, documentary or otherwise, required of him, may tend to criminate him or subject him to a penalty or forfeiture. But no person shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter or thing, concerning which he may testify, or produce evidence, documentary or otherwise, before said Commission, or in obedience to its subpoena ... or in any such case or proceeding: Provided, That no person so testifying shall be exempt from prosecution and punishment for perjury committed in so testifying.”
Shiras, J., joined by Gray and White, JJ., and Field, J., dissented.
It is true that the Court in Brown v. Walker stated: “. . . it is entirely clear that he was not the chief or even a substantial offender against the law, and that his privilege was claimed for the purpose of shielding the railway or its officers from answering a charge of having violated its provisions. To say that, notwithstanding his immunity from punishment, he would incur personal odium and disgrace from answering these questions, seems too much like an abuse of language to be worthy of serious consideration.” 161 U. S., at 609-610. The Court, however, concluded: “But, even if this were true, under the authorities above cited, he would still be compelled to answer, if the facts sought to be elucidated were material to the issue.” Id., at 610. For a fuller exposition, see id., at 605-606.
“(a) In the course of any investigation relating to any interference with or endangering of, or any plans or attempts to interfere with or endanger the national security or defense of the United States by treason, sabotage, espionage, sedition, seditious conspiracy or the overthrow of its Government by force or violence, no witness shall be excused from testifying or from producing books, papers, or other evidence before either House, or before any committee of either House, or before any joint committee of the two Houses of Congress on the ground that the testimony or evidence required of him may tend to incriminate him or subject him to a penalty or forfeiture, when the record shows that—
“(1) in the case of proceedings before one of the Houses of Congress, that a majority of the members present of that House; or
“(2) in the case of proceedings before a committee, that two-thirds of the members of the full committee shall by affirmative vote have authorized such witness to be granted immunity under this section with respect to. the transactions, matters, or things concerning which he is compelled, after having claimed his privilege against self-incrimination to testify or produce evidence by direction of the presiding officer and
“that an order of the United States district court for the district wherein the inquiry is being carried on has been entered into the record requiring said person to testify or produce evidence. Such an order may be issued by a United States district court judge upon application by a duly authorized representative of the Congress or of the committee concerned. But no such witness shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter, or thing concerning which he is so compelled, after having claimed his privilege against self-incrimination, to testify or produce evidence, nor shall testimony so compelled be used as evidence in any criminal proceeding (except prosecutions described in subsection (d) hereof) against him in any court.
“(b) Neither House nor any committee thereof nor any joint committee of the two Houses of Congress shall grant immunity to any witness without first having notified the Attorney General of the United States of such action and thereafter having secured the approval of the United States district court for the district wherein such inquiry is being held. The Attorney General of the United States shall be notified of the time of each proposed application to the United States district court and shall be given the opportunity to be heard with respect thereto prior to the entrance into the record of the order of the district court.”
The footnotes in the district judge’s opinion have been renumbered.
“Crowell v. Benson, 285 U. S. 22, 62 . . . United States v. Rumely, 345 U. S. 41, 45 . . . United States v. C. I. O., 335 U. S. 106 . . . Brandeis, J. concurring in Ashwander v. T. V. A., 297 U. S. 288, 341, 348 . . . and cases cited.”
“United States v. Rumely, 345 U. S. 41, 47 . . . .”
“Cf. Shapiro v. United States, 335 U. S. 1, 31 . . . .”
We need not consider at this time petitioner’s claim that immunity is not complete and the statute unconstitutional because he can be prosecuted later for participation in a continuing conspiracy. Congress has the power to provide, and has provided, that immunity from prosecution which the Constitution requires. See Heike v. United States, 227 U. S. 131, 142.
He urged that the statute left the witness in a worse condition because it did not abrogate the crime for which he was given immunity; that the constitutional safeguard goes toward relieving the witness from the danger of an accusation being made against him while the statutory immunity forces him to supply evidence leading to an accusation and provides only a means for defense; that the statute puts a heavy burden on petitioner, if he is indicted, to prove that he had testified concerning the matter for which he was indicted; that a citizen is entitled to the very thing secured to him by the constitutional safeguards and not something which will probably answer the same purpose; that the statute subjects him to the infamy and disgrace from which he was protected by the constitutional safeguard; that the statute did not protect him from prosecution for a state crime; that even if it were so interpreted, Congress had no power to grant such protection; that the immunity granted was too narrow since it only extended to matters concerning which he was called to testify and not to all matters related to the testimony given; that to be able to claim the privilege the witness would virtually have to reveal his crime in order that the court could see that the statute failed to protect him; and finally that the statute was an attempt to exercise the power of pardon which was a power not delegated to Congress.
“. . . the provisions of the Constitution are not mathematical formulas having their essence in their form; they are organic living institutions transplanted from English soil. Their significance is vital not formal; it is to be gathered not simply by taking the words and a dictionary, but by considering their origin and the line of their growth.” Gompers v. United States, 233 U. S. 604, 610.
We do not discuss petitioner’s argument, relying on the First Amendment, that inquiry into his political membership and associations is unconstitutional. Petitioner contends that some of the questions which he was asked are objectionable because they require testimony that is protected by the implications of the First Amendment. But it is every man’s duty to give testimony before a duly constituted tribunal unless he invokes some valid legal exemption in withholding it. Although petitioner made the First Amendment argument when the United States Attorney applied, under the Immunity Act, for an order requiring him to testify, when he was cited for contempt he urged only “all of the grounds we urged before Judge Weinfeld in opposition to the statute, in support of our contention that the statute was unconstitutional. We will rest on that and proceed on that basis in the Appellate Courts.” Petitioner did not make any objection to the questions other than the assertion of the unconstitutionality of the Immunity Act. It should also be noted that when petitioner — who, the record shows, was an experienced witness, had been advised by counsel especially experienced in this field, and was desirous of making this a test case — refused to answer the questions propounded before the grand jury the second time, he did not claim any privilege under the First Amendment. His counsel, by way of dispensing with the reading of the minutes of what took place before the grand jury, stated that “the reason given for his refusal was that he feared the answers might incriminate him and he pleaded his privilege under the Fifth Amendment of the Constitution.”