opinion: Mr. Justice Brennan
  delivered the opinion of the Court.
  These cases present challenges to the validity of adjudications of civil contempt, pursuant to 28 U. S. C. § 1826 (a), of witnesses before federal grand juries who refused to comply with court orders to testify. The refusals were defended upon the ground that interrogation was to be based upon information obtained from the witnesses’ communications, allegedly intercepted by federal agents by means of illegal wiretapping and electronic surveillance. A provision of Title III of the Omnibus Crime Control and Safe Streets Act of 1968, 82 Stat. 211, as amended, 18 U. S. C. §§ 2510-2520, directs that “[w]henever any wire or oral communication has been intercepted, no part of the contents of such communication and no evidence derived therefrom may be received in evidence in any . . . proceeding in or before any . . . grand jury ... if the disclosure of that information would be in violation of this chapter.” 18 U. S. C. § 2515. The question presented is whether grand jury witnesses, in proceedings under 28 U. S. C. § 1826 (a), are entitled to invoke this prohibition of § 2515 as a defense to contempt charges brought against them for refusing to testify. In No. 71-110, the Court of Appeals for the Ninth Circuit held that they are not entitled to do so. United States v. Gelbard, 443 F. 2d 837 (1971). In No. 71-263, the Court of Appeals for the Third Circuit, en banc, reached the contrary conclusion. In re Grand Jury Proceedings, Harrisburg, Pennsylvania {Egan), 450 F. 2d 199 (1971); In re Grand Jury Proceedings, Harrisburg, Pennsylvania (Walsh), 450 F. 2d 231 (1971). We granted certiorari. 404 U. S. 990 (1971). We disagree with the Court of Appeals for the Ninth Circuit and agree with the Court of Appeals for the Third Circuit.
  No. 71-110. A federal district judge approved wiretaps by federal agents of the telephones of Perry Paul, an alleged bookmaker, and Jerome Zarowitz, a former executive of a Las Vegas casino. In the course of those taps, the agents overheard conversations between Paul and petitioner Gelbard and between Zarowitz and petitioner Parnas. Petitioners were subsequently called before a federal grand jury convened in Los Angeles to investigate possible violations of federal gambling laws. The Government asserted that petitioners would be questioned about third parties and that the questions would be based upon petitioners’ intercepted telephone conversations. Petitioners appeared before the grand jury, but declined to answer any questions based upon their intercepted conversations until they were afforded an opportunity to challenge the legality of the interceptions. Following a hearing, the United States District Court for the Central District of California found petitioners in contempt and, pursuant to 28 U. S. C. § 1826 (a), committed them to custody for the life of the grand jury or until they answered the questions.
  No. 71-263. Respondents Egan and Walsh were called before a federal grand jury convened in Harrisburg, Pennsylvania, to investigate, among other possible crimes, an alleged plot to kidnap a Government official. Pursuant to 18 U. S. C. § 2514, both respondents were granted transactional immunity in return for their testimony. Respondents appeared before the grand jury, but refused to answer questions on the ground, among others, that the questions were based upon information overheard from respondents by means of the Government’s illegal wiretapping and electronic surveillance. The Government did not reply to respondents’ allegations. Following a hearing, the United States District Court for the Middle District of Pennsylvania found respondents in contempt, and they were also committed to custody pursuant to 28 U. S. C. § 1826 (a).
  Section 1826 (a) expressly limits the adjudication of civil contempt to the case of a grand jury witness who “refuses without just cause shown to comply with an order of the court to testify.” Our inquiry, then, is whether a showing that interrogation would be based upon the illegal interception of the witness’ communications constitutes a showing of “just cause” that precludes a finding of contempt. The answer turns on the construction of Title III of the Omnibus Crime Control Act.
  I
  In Title III, Congress enacted a comprehensive scheme for the regulation of wiretapping and electronic surveillance. See United States v. United States District Court, 407 U. S. 297, 301-306. Title III authorizes the interception of private wire and oral communications, but only when law enforcement officials are investigating specified serious crimes and receive prior judicial approval, an approval that may not be given except upon compliance with stringent conditions. 18 U. S. C. §§2516, 2518 (l)-(8). If a wire or oral communication is intercepted in accordance with the provisions of Title III, the contents of the communication may be disclosed and used under certain circumstances. 18 U. S. C. § 2517. Except as expressly authorized in Title III, however, all interceptions of wire and oral communications are flatly prohibited. Unauthorized interceptions and the disclosure or use of information obtained through unauthorized interceptions are crimes, 18 U. S. C. §2511 (1), and the victim of such interception, disclosure, or use is entitled to recover civil damages, 18 U. S. C. § 2520. Title III also bars the use as evidence before official bodies of the contents and fruits of illegal interceptions, 18 U. S. C. § 2515, and provides procedures for moving to suppress such evidence in various proceedings, 18 U. S. C. § 2518 (9) — (10).
  The witnesses in these cases were held in contempt for disobeying court orders by refusing to produce evidence — their testimony — before grand juries. Consequently, their primary contention is that § 2515, the evidentiary prohibition of Title III, afforded them a defense to the contempt charges. In addressing that contention, we must assume, in the present posture of these cases, that the Government has intercepted communications of the witnesses and that the testimony the Government seeks from them would be, within the meaning of § 2515, “evidence derived” from the intercepted communications. We must also assume that the communications were not intercepted in accordance with the specified procedures and thus that the witnesses' potential testimony would be “disclosure” in violation of Title III. See 18 U. S. C. §§2511 (1), 2517 (3). In short, we proceed on the premise that § 2515 prohibits the presentation to grand juries of the compelled testimony of these witnesses.
  The narrow question, then, is whether under these circumstances the witnesses may invoke the prohibition of § 2515 as a defense to contempt charges brought on the basis of their refusal to obey court orders to testify. We think they may.
  The unequivocal language of § 2515 expresses the fundamental policy adopted by Congress on the subject of wiretapping and electronic surveillance. As the congressional findings for Title III make plain, that policy is strictly to limit the employment of those techniques of acquiring information:
  “To safeguard the privacy of innocent persons, the interception of wire or oral communications where none of the parties to the communication has consented to the interception should be allowed only when authorized by a court of competent jurisdiction and should remain under the control and supervision of the authorizing court. Interception of wire and oral communications should further be limited to certain major types of offenses and specific categories of crime with assurances that the interception is justified and that the information obtained thereby will not be misused.” § 801 (d), 82 Stat. 211.
  The Senate committee report that accompanied Title III underscores the congressional policy:
  “Title III has as its dual purpose (1) protecting the privacy of wire and oral communications, and (2) delineating on a uniform basis the circumstances and conditions under which the interception of wire and oral communications may be authorized. To assure the privacy of oral and wire communications, title III prohibits all wiretapping and electronic surveillance by persons other than duly authorized law enforcement officers engaged in the investigation or prevention of specified types of serious crimes, and only after authorization of a court order obtained after a showing and finding of probable cause.” S. Rep. No. 1097, 90th Cong., 2d Sess., 66 (1968).
  Hence, although Title III authorizes invasions of individual privacy under certain circumstances, the protection of privacy was an overriding congressional concern. Indeed, the congressional findings articulate clearly the intent to utilize the evidentiary prohibition of § 2515 to enforce the limitations imposed by Title III upon wiretapping and electronic surveillance:
  “In order to protect effectively the privacy of wire and oral communications, to protect the integrity of court and administrative proceedings, and to prevent the obstruction of interstate commerce, it is necessary for Congress to define on a uniform basis the circumstances and conditions under which the interception of wire and oral communications may be authorized, to prohibit any unauthorized interception of such communications, and the use of the contents thereof in evidence in courts and administrative proceedings.” § 801(b), 82 Stat. 211 (emphasis added).
  And the Senate report, like the congressional findings, specifically addressed itself to the enforcement, by means of § 2515, of the limitations upon invasions of individual privacy:
  “Virtually all concede that the use of wiretapping or electronic surveillance techniques by private unauthorized hands has little justification where communications are intercepted without the consent of one of the participants. No one quarrels with the proposition that the unauthorized use of these techniques by law enforcement agents should be prohibited. . . . Only by striking at all aspects of the problem can privacy be adequately protected. The prohibition, too, must be enforced with all appropriate sanctions. Criminal penalties have their part to play. But other remedies must be afforded the victim of an unlawful invasion of privacy. Provision must be made for civil recourse for damages. The perpetrator must be denied the fruits of his unlawful actions in civil and criminal proceedings. Each of these objectives is sought by the proposed legislation.” S. Rep. No. 1097, supra, at 69 (emphasis added).
  Section 2515 is thus central to the legislative scheme. Its importance as a protection for “the victim of an unlawful invasion of privacy” could not be more clear. The purposes of § 2515 and Title III as a whole would be subverted were the plain command of § 2515 ignored when the victim of an illegal interception is called as a witness before a grand jury and asked questions based upon that interception. Moreover, § 2515 serves not only to protect the privacy of communications, but also to ensure that the courts do not become partners to illegal conduct: the evidentiary prohibition was enacted also “to protect the integrity of court and administrative proceedings.” Consequently, to order a grand jury witness, on pain of imprisonment, to disclose evidence that § 2515 bars in unequivocal terms is both to thwart the congressional objective of protecting individual privacy by excluding such evidence and to entangle the courts in the illegal acts of Government agents.
  In sum, Congress simply cannot be understood to have sanctioned orders to produce evidence excluded from grand jury proceedings by § 2515. Contrary to the Government's assertion that the invasion of privacy is over and done with, to compel the testimony of these witnesses compounds the statutorily proscribed invasion of their privacy by adding to the injury of the interception the insult of compelled disclosure. And, of course, Title III makes illegal not only unauthorized interceptions, but also the disclosure and use of information obtained through such interceptions. 18 U. S. C. §2511(1); see 18 U. S. C. § 2520. Hence, if the prohibition of § 2515 is not available as a defense to the contempt charge, disclosure through compelled testimony makes the witness the victim, once again, of a federal crime. Finally, recognition of § 2515 as a defense “relieves judges of the anomalous duty of finding a person in civil contempt for failing to cooperate with the prosecutor in a course of conduct which, if pursued unchecked, could subject the prosecutor himself to heavy civil and criminal penalties.” In re Grand, Jury Proceedings, Harrisburg, Pennsylvania (Egan), 450 F. 2d, at 220 (Rosenn, J., concurring). “And for a court, on petition of the executive department, to sentence a witness, who is herself the victim of the illegal wiretapping, to jail for refusal to participate in the exploitation of that crime in violation of the explicit command of Section 2515 is to stand our whole system of criminal justice on its head.” In re Evans, 146 U. S. App. D. C. 310, 323, 452 F. 2d 1239, 1252 (1971) (Wright, J., concurring).
  II
  Our conclusion that § 2515 is an available defense to the contempt charge finds additional support in 18 U. S. C. § 3504, enacted as part of the Organized Crime Control Act of 1970, 84 Stat. 935. Section 3504 is explicit confirmation that Congress intended that grand jury witnesses, in reliance upon the prohibition of § 2515, might refuse to answer questions based upon the illegal interception of their communications.
  Section 3504 provides:
  “(a) In any . . . proceeding in or before any . . . grand jury ....
  “(1) upon a claim by a party aggrieved that evidence is inadmissible because it is the primary product of an unlawful act or because it was obtained by the exploitation of an unlawful act, the opponent of the claim shall affirm or deny the occurrence of the alleged unlawful act.”
  Under § 3504 (a) (2), disclosure of information relating to the claim of inadmissibility is not mandatory if the “unlawful act” took place before June 19, 1968, the effective date of Title III. Under §3504 (a) (3), there is a five-year limitation upon the consideration of a claim of inadmissibility based upon “the exploitation of an unlawful act” that took place before June 19, 1968. Section 3504 (b), by reference to Title III, defines an “unlawful act” as one involving illegal wiretapping or electronic surveillance.
  Section 3504, then, establishes procedures to be followed “upon a claim by a party aggrieved that evidence is inadmissible because” of an illegal interception. And § 3504 tracks § 2515 in its application to grand jury proceedings. Indeed, “[t]he language used in defining the types of proceedings, types of forums, and jurisdictions in which section 3504 is applicable was taken from 18 U. S. C. §2515.” S. Rep. No. 91-617, p. 154 (1969). In the application of § 3504 to “any . . . proceeding in or before any . . . grand jury,” “a party aggrieved” can only be a witness, for there is no other “party” to a grand jury proceeding. Moreover, a “claim . . . that evidence is inadmissible” can only be a claim that the witness’ potential testimony is inadmissible. Hence, § 3504, by contemplating “a claim by a party aggrieved that evidence is inadmissible because” of an illegal interception, necessarily recognizes that grand jury witnesses may rely upon the prohibition of § 2515 in claiming that the evidence sought from them is inadmissible in the grand jury proceedings. Upon such a claim by a grand jury witness, the Government, as “the opponent of the claim,” is required under § 3504 (a)(1) to “affirm or deny the occurrence of the alleged” illegal interception. Section 3504 thus confirms that Congress meant that grand jury witnesses might defend contempt charges by invoking the prohibition of § 2515 against the compelled disclosure of evidence obtained in violation of Title III.
  The Government urges, however, that the procedures prescribed in § 3504 are limited in application to claims of inadmissibility based upon illegal interceptions that took place before June 19, 1968, and that § 3504 cannot, therefore, provide support for a construction of § 2515. We disagree. While subsections (a) (2) and (a) (3) apply only when the illegal interception took place before June 19, 1968, it is clear both from the face of § 3504 and from its legislative history that subsection (a)(1), imposing the duty upon “the opponent of the claim” to “affirm or deny the occurrence of the alleged” illegal interception, is not similarly limited.
  The omission of the June 19, 1968, date from subsection (a)(1) was not inadvertent. Subsection (a)(1) was not in the original Senate bill, although the bill did contain counterparts of present subsections (a)(2) and (a) (3) without the June 19, 1968, or any other date limitation. See Hearings before the Subcommittee on Criminal Laws and Procedures of the Senate Committee on the Judiciary on S. 30 et al., 91st Cong., 1st Sess., 102-105 (1969). Subsection (a)(1) was added at the suggestion of the Department of Justice. At that time the Department followed the practice of searching Government files for information about wiretaps and eavesdropping. The Department advised the Senate Judiciary Committee that while it had been “conducting] such examinations as a matter of policy even in cases where no motion ha[d] been filed . . . defendants should be assured such an examination by a specific requirement of law rather than hav[ing] to rely upon the continued viability of a current policy.” Id., at 553. The Senate report on § 3504 explained that “since [subsection (a)(1)] requires a pending claim as a predicate to disclosure, it sets aside the present wasteful practice of the Department of Justice in searching files without a motion from a defendant.” S. Rep. No. 91-617, p. 154 (1969).
  The reason assigned in the Senate for enacting subsection (a)(1) was thus as applicable to post- as it was to pre-June 19, 1968, interceptions. The same was true of the House. There subsection (a)(1) was supported on the ground that it would be beneficial to the victims of illegal interceptions. Senator McClellan, for example, who testified before the House Subcommittee, indicated that subsection (a)(1) “places upon the Government an affirmative duty to answer a claim that evidence is inadmissible because of unlawful investigative conduct.” “The first requirement [of § 3504], that the Government admit or deny the occurrence of the alleged invasion of the defendant’s rights, actually places or codifies a burden upon the Government, rather than the defendant.” Hearings before Subcommittee No. 5 of the House Committee on the Judiciary on S. 30 et al., 91st Cong., 2d Sess., 84, 104 (1970). Other witnesses thought the provision unnecessary. Indeed, one organization submitted a report that disapproved subsection (a)(1) on the ground that the Government should admit illegalities without a prior claim. Id., at 562 (Section of Criminal Law of the American Bar Association). It is also significant that congressional questioning of a representative of the Department of Justice at the hearings was directed to the Department’s views on the insertion of a date limitation only in subsections (a)(2) and (a)(3). Id., at 659; see the Department’s written response, id., at 675-676.
  The June 19, 1968, date was inserted in subsections (a) (2) and (a) (3) after the conclusion of the House hearings. It is apparent from the House report that only subsections (a) (2) and (a) (3) of the Senate version were to be limited by the June 19, 1968, date and that subsection (a)(1) was to be operative without regard to when the alleged illegal interception may have taken place:
  "Paragraph (1) provides that upon a claim by an aggrieved party that evidence is inadmissible because it is the primary product of an unlawful act, or because it was obtained by the exploitation of an unlawful act, the opponent of the claim must affirm or deny the occurrence of the alleged unlawful act. Under this provision, upon a charge by the defendant with standing to challenge the alleged unlawful conduct, the Government would be required to affirm or deny that an unlawful act involving electronic surveillance had in fact occurred. If such an unlawful act had in fact occurred, paragraph (2), below, will govern disclosure of the contents of the electronic surveillance records or transcripts to the defendant and his counsel, unless paragraph (3) applies.” H. R. Rep. No. 91-1549, p. 51 (1970).
  This explanation demonstrates that “the opponent of the claim” has a duty to “affirm or deny” whenever “a party aggrieved” “claim [s] . . . that evidence is inadmissible because it is” derived from an illegal interception. The date June 19, 1968, becomes relevant only after it is determined that an illegal interception took place and an issue thus arises as to disclosure of information bearing on the claim.
  III
  The Government argues, finally, that while § 2515 could be construed to allow a grand jury witness to invoke its prohibition as a defense to a contempt charge, “[i]f this section were the only relevant portion of [Title III],” Brief for the United States in No. 71-263, p. 19, proceedings before grand juries are omitted from another provision of Title III, § 2518 (10) (a), that authorizes “[a]ny aggrieved person,” in specified types of proceedings, to “move to suppress the contents of any intercepted wire or oral communication, or evidence derived therefrom.” But it does not follow from the asserted omission of grand jury proceedings from the suppression provision that grand jury witnesses cannot invoke § 2515 as a defense in a contempt proceeding under 28 U. S. C. § 1826 (a). The congressional concern with the applicability of §2518 (10) (a) in grand jury proceedings, so far as it is discernible from the Senate report, was apparently that defendants and potential defendants might be able to utilize suppression motions to impede the issuance of indictments: “Normally, there is no limitation on the character of evidence that may be presented to a grand jury, which is enforcible by an individual. [United States v. Blue, 384 U. S. 251 (1966).] There is no intent to change this general rule.” S. Rep. No. 1097, 90th Cong., 2d Sess., 106 (1968). The “general rule,” as illustrated in Blue, is that a defendant is not entitled to have his indictment dismissed before trial simply because the Government “acquire [d] incriminating evidence in violation of the [law],” even if the “tainted evidence was presented to the grand jury.” 384 U. S., at 255 and n. 3; see Lawn v. United States, 355 U. S. 339 (1958); Costello v. United States, 350 U. S. 359 (1956). But that rule has nothing whatever to do with the situation of a grand jury witness who has refused to testify and attempts to defend a subsequent charge of contempt. Hence, we cannot agree that the Senate report expressed the view that a grand jury witness would be foreclosed from raising the § 2515 defense in a contempt proceeding under § 1826 (a).
  Furthermore, grand jury witnesses do not normally discover whether they may refuse to answer questions by filing motions to suppress their potential testimony. The usual procedure is, upon the Government’s motion, to have a court order a grand jury witness to testify upon penalty of contempt for noncompliance. Section 1826 (a) embodies that traditional procedure. The asserted omission of grand jury proceedings from § 2518 (10) (a) may well reflect congressional acceptance of that procedure as adequate in these cases. Consequently, we cannot suppose that Congress, by providing procedures for suppression motions, intended to deprive grand jury witnesses of the § 2515 defense that would otherwise be available to them. Although the Government points to statements in the Senate report to the effect that §2518 (10) (a) “limits” §2515, we read those statements to mean that suppression motions, as a method of enforcing the prohibition of § 2515, must be made in accordance with the restrictions upon forums, procedures, and grounds specified in §2518 (10)(a).
  The judgment of the Court of Appeals for the Ninth Circuit in No. 71-110 is reversed, and the case is remanded for further proceedings consistent with this opinion. The judgment of the Court of Appeals for the Third Circuit in No. 71-263 is affirmed.
  It is so ordered.
  Section 1826 (a) provides:
  “Whenever a witness in any proceeding before or ancillary to any court or grand jury of the United States refuses without just cause shown to comply with an order of the court to testify or provide other information, including any book, paper, document, record, recording or other material, the court, upon such refusal, or when such refusal is duly brought to its attention, may summarily order his confinement at a suitable place until such time as the witness is willing to give such testimony or provide such information. No period of such confinement shall exceed the life of—
  “(1) the court proceeding, or
  “(2) the term of the grand jury, including extensions,
  “before which such refusal to comply with the court order occurred, but in no event shall such confinement exceed eighteen months.” This provision was enacted as part of the Organized Crime Control Act of 1970. It was intended to codify the existing practice of the federal courts. S. Rep. No. 91-617, pp. 33,. 56-57, 148-149 (1969); H. R. Rep. No. 91-1549, pp. 33, 46 (1970); see Shillitani v. United States, 384 U. S. 364 (1966).
  Section 2515 provides in full:
  “Whenever any wire or oral communication has been intercepted, no part of the contents of such communication and no evidence derived therefrom may be received in evidence in any trial, hearing, or other proceeding in or before any court, grand jury, department, officer, agency, regulatory body, legislative committee, or other authority of the United States, a State, or a political subdivision thereof if the disclosure of that information would be in violation of this chapter.”
  The Third Circuit followed Egan in In re Grand Jury Investigation (Maratea), 444 F. 2d 499 (1971) (en banc). The District of Columbia Circuit has aligned itself with the Third, see In re Evans, 146 U. S. App. D. C. 310, 452 F. 2d 1239 (1971), while the Ninth has continued to follow Gelbard, see Bacon v. United States, 446 F. 2d 667 (1971); Olsen v. United States, 446 F. 2d 912 (1971); In re Russo, 448 F. 2d 369 (1971); Reed v. United States, 448 F. 2d 1276 (1971); United States v. Reynolds, 449 F. 2d 1347 (1971). The First and Fifth Circuits have also adverted to the question. United States v. Doe (In re Marx), 451 F. 2d 466 (CA1 1971); United States v. Doe (In re Popkin), 460 F. 2d 328 (CA1 1972); Dudley v. United States, 427 F. 2d 1140 (CA5 1970). See also United States ex rel. Rosado v. Flood, 394 F. 2d 139 (CA2 1968); Carter v. United States, 417 F. 2d 384 (CA9 1969).
  See n. 23, injra.
  In view of our disposition of these cases, we do not reach any of the constitutional issues tendered as to the right of a grand jury witness to rely upon the Fourth Amendment as a basis for refusing to answer questions. We also note that the constitutionality of Title III is not challenged in these cases.
  “Paragraph (d) recognizes the responsible part that the judiciary must play in supervising the interception of wire or oral communications in order that the privacy of innocent persons may be protected: . . . the interception or use of wire or oral communications should only be on court order. Because of the importance of privacy, such interceptions should further be limited to major offenses and care must be taken to insure that no misuse is made of any information obtained.” S. Rep. No. 1097, 90th Cong., 2d Sess., 89 (1968).
  In stating the problem addressed by Congress in Title III, the Senate report noted that “[b]oth proponents and opponents of wiretapping and electronic surveillance agree that the present state of the law in this area is extremely unsatisfactory and that the Congress should act to clarify the resulting confusion.” Id., at 67. The report agreed: “It would be, in short, difficult to devise a body of law from the point of view of privacy or justice more totally unsatisfactory in its consequences.” Id.., at 69. The report then stressed that Title III would provide the protection for privacy lacking under the prior law:
  “The need for comprehensive, fair and effective reform setting uniform standards is obvious. New protections for privacy must be enacted. Guidance and supervision must be given to State and Federal law enforcement officers. This can only be accomplished through national legislation. This the subcommittee proposes.” Ibid, (emphasis added).
  “Paragraph (b) recognizes that to protect the privacy of wire and oral communications, to protect the integrity of court and administrative proceeding]^] and to prevent the obstruction of interstate commerce, it is necessary for Congress to define on a uniform basis the circumstances and conditions under which the interception of wire or oral communications may be authorized. It also finds that all unauthorized interception of such communications should be prohibited, as well as the use of the contents of unauthorized interceptions as evidence in courts and administrative hearings.” Id., at 89 (emphasis added).
  “Section 2515 of the new chapter imposes an evidentiary sanction to compel compliance with the other prohibitions of the chapter. It provides that intercepted wire or oral communications or evidence derived therefrom may not be received in evidence in any proceeding before any court, grand jury, department, officer, agency, regulatory body, legislative committee, or other authority of the United States, a State, or a political subdivision of a State, where the disclosure of that information would be in violation of this chapter. . . . [I]t is not limited to criminal proceedings. Such a suppression rule is necessary and proper to protect privacy. The provision thus forms an integral part of the system of limitations designed to protect privacy. Along with the criminal and civil remedies, it should serve to guarantee that the standards of the new chapter will sharply crfrtail the unlawful interception of wire and oral communications.” Id,., at 96 (citations omitted).
  Congressional concern with the protection of the privacy of communications is evident also in the specification of what is to be protected. “The proposed legislation is intended to protect the privacy of the communication itself . . . Id., at 90. As defined in Title III, “ 'contents/ when used with respect to any wire or oral communication, includes any information concerning the identity of the parties to such communication or the existence, substance, purport, or meaning of that communication.” 18 U. S. C. § 2510 (8). The definition thus “include[s] all aspects of the communication itself. No aspect, including the identity of the parties, the substance of the communication between them, or the fact of the communication itself, is excluded. The privacy of the communication to be protected is intended to be comprehensive.” S. Rep. No. 1097, supra, at 91.
  Section 3504 provides in full:
  “(a) In any trial, hearing, or other proceeding in or before any court, grand jury, department, officer, agency, regulatory body, or other authority of the United States—
  “(1) upon a claim by a party aggrieved that evidence is inadmissible because it is the primary product of an unlawful act or because it was obtained by the exploitation of an unlawful act, the opponent of the claim shall affirm or deny the occurrence of the alleged unlawful act;
  “(2) disclosure of information for a determination if evidence is inadmissible because it is the primary product of an unlawful act occurring prior to June 19, 1968, or because it was obtained by the exploitation of an unlawful act occurring prior to June 19, 1968, shall not be required unless such information may be relevant to a pending claim of such inadmissibility; and
  “(3) no claim shall be considered that evidence of an event is inadmissible on the ground that such evidence was obtained by the exploitation of an unlawful act occurring prior to June 19, 1968, if such event occurred more than five years after such allegedly unlawful act.
  '■'(b) As used in this section 'unlawful act' means any act [involving] the use of any electronic, mechanical, or other device (as defined in section 2510 (5) of this title) in violation of the Constitution or laws of the United States or any regulation or standard promulgated pursuant thereto.”
  No question as to the constitutionality of §3504 is raised in these cases.
  “The only exception is that section 350 [4] omits legislative committees.” S. Rep. No. 91-617, p. 154 (1969). In addition, the House amended § 3504, as passed by the Senate, so that, unlike § 2515, it “applies only to trials and other proceedings conducted under authority of the United States.” H. R. Rep. No. 91-1549, p. 51 (1970).
  The references to June 19, 1968, appear only in subsections (a) (2) and (a)(3). Subsection (a)(1) does not similarly limit the term “unlawful act” with the phrase “occurring prior to June 19, 1968.” See n. 11, supra. It is thus plain on the face of § 3504 that Congress did not make the duty imposed by subsection (a) (1) dependent upon the date of the alleged illegal interception.
  The Senate passed § 3504 in a form that, so far as is pertinent to the issue before us, differed from the section as finally enacted only in that subsections (a) (2) and (a) (3) in the Senate version were not limited in application to illegal interceptions that took place before June 19, 1968. See S. Rep. No. 91-617, pp. 15,. 70 (1969).
  “[Subsection (a)(1)] provides that in an attack upon the admissibility of evidence because it is the product of an unlawful act ... , the opponent of such claim shall affirm or deny the alleged unlawful act ... . In this respect. [§ 3504] is unnecessary.” Hearings before Subcommittee No. 5 of the House Judiciary Committee on S. 30 et al., 91st Cong., 2d Sess., 399 (1970) (report of the Committee on Federal Legislation of the New York County Lawyers’ Association). “That is the law now by Supreme Court decision. [Subsection (a)(1)] adds nothing to what exists right now.” Id., at 513 (testimony of Lawrence Speiser, representing the American Civil Liberties Union).
  Congress, of course, was primarily concerned' with “certain evidentiary problems created by electronic surveillance conducted by the Government prior to the enactment of [Title III] on June 19, 1968, which provided statutory authority for obtaining surveillance warrants in certain types of criminal investigations (18 U. S. C. 2516).” H. R. Rep. No. 91-1549, p. 50 (1970). As the Senate report noted, however, §3504 applies to "[c]ivil as well as criminal proceedings . . . , regardless of whether a government or governmental body or officer is or is not a party or witness.” S. Rep. No. 91-617, p. 154 (1969). Moreover, “unlawful acts,” as defined in §3504 (b), may be “acts of private citizens, as well as acts of Federal or State officials.” Ibid.
  “Under paragraph (2) disclosure of the information shall be required to be made to a defendant who has demonstrated the illegality of the electronic surveillance (occurring prior to June 19, 1968) and his standing where such information is or 'may be’ relevant to a claim of inadmissibility. In cases where the electronic surveillance occurred on or after June 19, 1968, disclosure is mandatory where illegality and standing are demonstrated. The provision thus alters the procedure announced in Alderman v. United States, 394 U. S. 165 [(1969)] with respect to ‘unlawful acts’ committed prior to June 19, 1968.” H. R. Rep. No. 91-1549, p. 51 (1970).
  An “aggrieved person,” for purposes of § 2518 (10) (a), is “a person who was a party to any intercepted wire or oral communication or a person against whom the interception was directed.” 18 U. S. C. §2510 (11); see S. Rep. No. 1097, 90th Cong., 2d Sess., 91,106 (1968).
  Section 2518 (10) provides in pertinent part:
  “(a) Any aggrieved person in any trial, hearing, or proceeding in or before any court, department, officer, agency, regulatory body, or other authority of the United States, a State, or a political subdivision thereof, may move to suppress the contents of any intercepted wire or oral communication, or evidence derived therefrom . . . .”
  While on its face § 2518 (10) (a) applies to grand jury proceedings, when compared with the list of proceedings in § 2515, see n. 2, supra, it appears that “grand jury” was omitted from the list in §2518 (10)(a).
  “Because no person is a party as such to a grand jury proceeding, the provision does not envision the making of a motion to suppress in the context of such a proceeding itself. ... It is the intent of the provision only that when a motion to suppress is granted in another context, its scope may include use in a future grand jury proceeding.” S. Rep. No. 1097, 90th Cong., 2d Sess., 106 (1968). This assertion is not ambiguous, for motions to suppress evidence to be presented to a grand jury would presumably be made in court.
  “This definition [§ 2510 (11)] defines the class of those who are entitled to invoke the suppression sanction of section 2515 . . . through the motion to suppress provided for by section 2518 (10) (a) ... Id,., at 91. “The provision [§ 2515] must, of course, be read in light of section 2518 (10) (a) . . . which defines the class entitled to make a motion to suppress.” Id., at 96. “This provision [§ 2518 (10) (a)] must be read in connection with sections 2515 and 2517 . . . which it limits. It provides the remedy for the right created by section 2515.” Id., at 106.
  Because the District Court and the Court of Appeals erroneously held that grand jury witnesses have no right to invoke a § 2515 defense in contempt proceedings under § 1826 (a), we need not decide whether Gelbard and Pamas may refuse to answer questions if the interceptions of their conversations were pursuant to court order. That is a matter for the District Court to consider in the first instance.
  The Court of Appeals vacated the judgments of contempt and remanded for hearings to determine whether the questions asked respondents resulted from the illegal interception of their communications. 450 F. 2d, at 217. Although, in this Court, the Government now denies that there was any overhearing, in view of our affirmance that is a matter for the District Court to consider in the first instance.