delivered the opinion of the Court. .
This contempt of Congress case, stemming from investigations conducted by the House Committee on UnAmerican Activities, involves, among others, questions of whether the House Committee on Un-American Activities failed to comply with its rules and whether such a failure excused petitioner’s refusal to answer the Committee’s questions.
*111Petitioner Edward Yellin Was indicted in the Northern District of Indiana on five counts of willfully refusing to answer questions put to him by a Subcommittee of the House Committee on Un-American Activities (hereafter Committee) at a public hearing. He was convicted, under 2 U. S. C. § 192, of contempt of Congress on four counts. He was sentenced to four concurrent terms of imprisonment, each for one year, and fined $250. The Court of Appeals for the Seventh Circuit affirmed. 287 F. 2d 292. Since the case presented constitutional questions of continúing importance, we granted certiorari. 368 U. S. 816. However, because of the view we take of the Committee’s action, which was at variance with its rules, we do not reach the constitutional questions raised.1
The factual setting is for the most part not in dispute. The Committee was engaged, in 1958, in an investigation of so-called colonization by the Communist Party in basic industry. One of its inquiries focused upon the steel industry in Gary, Indiana, where petitioner was employed. Having information that petitioner was a Communist, the Committee decided to call Yellin and question him in a public rather than an executive session. The Committee then subpoenaed petitioner on January 23,1958. His attorney, Mr. Rabinowitz, sent a telegram to the Committee’s general counsel, Mr. Tavenner, on Thursdajr, February 6, 1958. The telegram asked for an executive session because "testimony needed for legislative . . . purposes can be secured in executive session without exposing witnesses to publicity.” Since the Committee and *112Mr. Tavenner had left Washington, D. C., for Gary, the telegram was answered by the Committee’s Staff Director. His reply read:
“Reurtel [Re your telegram?] requesting executive session in lieu of open session for Edward Yellin and Nicholas Busic. Your request denied.
“Richard Arens Staff Director”
According to Congressman Walter, the Chairman of the Committee, Mr. Arens did not have authority to take such action.
Petitioner’s counsel also sought to bring the matter to the Committee’s attention when it commenced its public' hearing the following Monday, February 10, 1958. His efforts to have the telegrams read into the record were cut short by Congressman Walter.2 Mr. Rabinowitz would not have been justified in continuing, since Committee rules permit counsel only to advise a witness, not to engage in oral argument with the Committee. Rule *113VII (B). In any event, Congressman Walter was not interested in discussing the content of the telegrams. From his sometimes conflicting testimony at trial, it appears he did not even know what the telegrams said.3 And though Congressman Walter said the Committee would consider in executive session whether to make the telegrams a part of the record, it appears that whatever *114action was taken was without knowledge of the telegrams’ contents.4
*112“The Chairman. Do not. bother. You know the privileges given you by this committee. You have appeared before it often enough. You know as well as anybody.- Go ahead, Mr. Tavenner.”
*114It is against this background that the Committee’s failure to comply with its own rules must be judged. It has been long settled, of course, that rules of Congress and its committees are, judicially cognizable. Christoffel v. United States, 338 U. S. 84; United States v. Smith, 286 U. S. 6; United States v. Ballin, 144 U. S. 1. And a legislative committee has been held to observance of its rules, Christoffel v. United States, supra, just as, more frequently, executive agencies have been. See, e. g., Vitarelli v. Seaton, 359 U. S. 535; Service v. Dulles, 354 U. S. 363.
The particular Committee Rule involved, Rule IV, provides in part:
“IV — Executive and Public Hearings:
“A — Executive:
“(1) If a majority of the Committee or Subcommittee, duly appointed as provided by the rules of the House of Representatives, believes that the interrogation of a witness' in a public hearing might *115endanger national security or unjustly injure his reputation, or the reputation of other individuals, the Committee shall interrogate such witness in an Executive Session for the purpose of determining' the necessity or advisability of conducting such interrogation thereafter in a public hearing.
. . . .
“B — Public Hearings:
“(1) All other hearings shall be public.” (Emphasis added.)
The rule is quite explicit in requiring that injury to a witness’ reputation be considered, along with danger to the national security and injury to the reputation of third parties, in deciding whether to hold an executive session.
At the threshold we are met with the argument that Rule IV was written to provide guidance for the Committee alone and that it was not designed to confer upon witnesses the right to request an executive session and the right to have the Committee act, either upon that request or on its own, according to the standards set forth in the rule'. It seems clear, from the structure of the Committee’s rules and from the Committee’s practice, that such is not the case.
The rules are few in number and brief — all 17 take little more than six pages in the record. Yet throughout the rulés the dominant theme is definition of the witness’ rights and privileges. Rule II requires that the subject of any investigation be announced and that information sought be “relevant and germane to the subject.” Rule III requires, that witnesses be subpoenaed “a reasonably sufficient time in advance” to allow them a chance to prepare and employ counsel. Rule VI makes available to any witness a transcript of his testimony — though at his expense. Rule VII gives every witness the privilege of having counsel advise him during the héaring. Rule VIII givés a witness a reasonable time to get other coun*116sel, if his original counsel is removed for failure to comply with the rules. Rule X makes detailed provision for those persons who have been named as subversive, Fascist, Communist, etc., by another witness. Such persons are given an opportunity to present rebuttal testimony and are to "be “accorded the same privileges as any other witness appearing before the Committee.” Rúle XIII permits any witness to keep out of the range of television cameras. Finally, Rule XVII requires that each witness “shall be furnished” a copy of the rules. All these work for the witness’ benefit. They show that the Committee has in a number of instances intended to assure a witness fair treatment, viz., the right to advice of counsel,; or protection from undue publicity, viz., the right not to be photographed by television cameras. Rule IV, in providing for an executive session when a public hearing might unjustly injure a witness’ reputation, has the same protective import. And if it is the witness who is being protected, the most logical person to have the right to enforce those protections is the witness himself.
The Committee’s practice reinforces this conclusion. Congressman Walter testified that the Committee “always” gave due consideration to requests for executive sessions.5 Weight should be given such a practice of *117the Committee in construing its rules, United States v. Smith, 286 U. S. 6, 33. That the Committee has entertained, and always does entertain, requests for executive sessions reinforces the conclusion that the Committee intended in Rule IV to give the individual witness a right to some consideration of his efforts to protect his reputation.
It must be acknowledged, of course, that Rule IV does not provide complete protection. The Committee may not be required by its rules to avoid even unjust injury to a witness’ reputation. Assuming that the Committee decides to hold an executive session, the Committee need do so only “for the purpose of determining the necessity or advisability of conducting such interrogation thereafter in a public hearing.” (Emphasis added.) By inclusion of the word “necessity” the rule may contemplate cases in which the Committee will proceed in a public hearing despite the risk or- even probability of injury to the witness’ reputation.6
*118That petitioner may be questioned in public, even after an executive session has been held, does not mean, however, that the 'Committee is freed from considering possible injury to his reputation. The Committee has at least undertaken to consider a witness’ reputation and the efforts a witness makes to protect it, even though the Committee may in its discretion nevertheless decide thereafter to hold a public hearing. The Committee failed in two respects to carry out that undertaking in Yellin’s case.
First, it does not appear from Congressman Walter’s testimony that the Committee considered injury to the witness’ reputation when it decided against calling Yellin in executive, session:
“Q. [By Mr. Rabinowitz] The Committee does sometimes hold executive sessions, doesn’t it?
“A. [By Congressman Walter] Yes.
“Q. And what are the considerations which the Committee uses in determining whether to hold executive sessions?
“A. This is usually done when the Committee is fearful lest a witness will mention the name of somebody against whom there' is no sworn testimony, and in order to prevent the name of somebody being mentioned in public that we are not sure has been active .in the conspiracy, at least that there isn’t sworn testimony to that effect, we have an executive hearing;
*119“Q. Are those theonly circumstances under which executive hearings are held?
“A. I don’t know of any, other, except that where we are fearful that testimony might be adduced that could be harmful to the national defense. We are not so sure about the testimony of any of the witnesses.” (Emphasis added.). .
By Congressman Walter’s own admission, the Committee holds executive sessions in only two of the three instances specified in Rule IV, i. e., when there may be injury to the reputation of a third party or injury to the national security. Injury to the witness himself is not a factor. Consequently the initial Committee decision to question Yellin publicly, made before serving him with a subpoena, was made without following Rule IV.
Secondly, the Committee failed to act upon petitioner’s express request for an executive session.7 The Staff Director, who lacked the authority to do so, acted in the Committee’s stead. That petitioner addressed his request to the Committee’s counsel does not alter the case. The Committee did not specify in Rule IV to whom such re*120quests should be addressed. But from other rules it maybe inferred that the general counsel is an appropriate addressee. In Rule IX, the Committee permits witnesses to file prepared or written statements for the record. The statements are' to be sent to the “counsel of the Committee.” Rule X makes provision for third parties who have been named as subversive, Fascist, Communist, etc., in a public hearing. A person, notified of having been named, who-feels that’his reputation has been adversely affected is directed to “[c]ommunicate with the counsel of the Committee.” As a footnote; to that rule, the Committee has said: “All witnesses are invited at any time to confer with Committee counsel or investigators for the Committee prior to hearings.” Also it should be noted that the Staff Director’s telegraphed response had the misleading appearance of authority and finality. The Chairman of the Committee should not now be. allowed to say that had petitioner disregarded the response he received from the Chairman’s staff and instead renewed his request to the Chairman, “this could not have happened” — especially when petitioner’s counsel tried to bring the matter to the attention of the Committee and was brusquely cut off.
Thus in two instances the Committee failed to exercise its discretion according to the standards which Yellin had a right to have considered. His position is similar to that of the petitioner in United States ex rel. Accardi v. Shaughnessy, 347 U. S. 260. Accardi had been ordered deported. Concededly the order was valid. However, Accardi applied to the Board of Immigration Appeals for suspension of the order. This, in the discretion of the Attorney General, was permitted by § 19 (c) of the Immigration Act of 1917, 39 Stat. 889, as amended, 8 TJ. S. C. (1946 ed., Supp. Y) § 155 (c). (The successor to that section in the 1952 Act is § 244, 66 Stat. 214, 8 TJ. S. C. *121§ 1254.) The Attorney General had by regulation permitted the Board of Immigration Appeals to make final decisions upon applications for this discretionary relief, subject to certain exceptions not involved in Accardi’s case. Shortly before petitioner appealed to the Board, the Attorney General published a list of “unsavory characters,” including petitioner, who were to be deported. Accardi claimed that since the Board knew he was on the list, it did not exercise the full discretion the Attorney General had delegated to it. Its decision was predetermined.
This' Court held that the Board had failed to exercise its discretion though required to do so by the Attorney General’s regulations. Although the Court recognized that Accardi might'well lose, even if the Board ignored -the Attorney General’s list of unsavory characters, it nonetheless held that Accardi should at least have the chance given him by the regulations.
The same result should obtain in the case at bar. Yellin might not prevail, even if the Committee takes note of the risk of injury to his reputation or his request for an executive session. But he is at least entitled to have the Committee follow its rules and give him consideration according to the standards it has adopted in Rule IY.
At that point, however, the similarity to Accardi’s case ends. Petitioner has no traditional remedy, such as the writ of habeas corpus upon which Accardi relied, by which to redress the loss of his rights; If the Committee ignores his request for an executive session, it is highly improbable that petitioner could obtain an injunction against the Committee that would protect him from public exposure. See Pauling v. Eastland, 109 U. S. App. D. C. 342, 288 F. 2d 126, cert. denied, 364 U. S. 900. Nor is there an administrative remedy for petitioner to pursue, should *122the Committee fail to consider the risk of injury to his reputation. To answer the questions put to him publicly and then seek redress is'no answer. For one thing, his testimony will cause the injury he seeks to avoid; under pain of perjury, he cannot by artful dissimulation evade revealing the information he wishes to remain confidential. For another, he. has no opportunity to recover in damages, U. S. Const., Art. I, § 6; Kilbourn v. Thompson,. 103 U. S. 168, 201-205. Cf. Tenney v. Brandhove, 341 U. S. 367, 377. Even the Fifth Amendment is not sufficient protection, since petitioner could say many things which would discredit him without subjecting himself to the risk of criminal prosecution-. The only avenue open is that which petitioner actually took. He refused to testify.
As a last obstacle, however, the Government argues that Yellin’s rights were forfeited by his failure to make, clear at the time he was questioned that his refusal to testify was based upon the Committee’s departure from Rule IV. Whatever the merits of the argument might be when immediately apparent deviations from Committee rules are involved,8 it has no application here. Yelliri was unable, at the time of his hearing, to tell from the actions of the Committee that his rights had been violated. So far as Yellin knew, the Staff Director acted as Congress*123man Walter’s agent, announcing the results of the Committee’s deliberations. And so far as he knew, the Committee, when it initially decided to hold a public hearing, did so in accordance with Rule IV. It was not until petitioner’s trial, when his attorney for the first time had an opportunity for searching examination, that it became apparent the Committee was violating its rules.
It may be assumed that if petitioner had expressly rested his refusal to answer upon a violation of Rule IV and the Committee nevertheless proceeded, he would be entitled to acquittal, were he able to prove his defense. Otherwise, if Yellin could be convicted of contempt of Congress notwithstanding the violation of Rule IV, he would be deprived of the only remedy he has for protect-. ing his reputation. Certainly the rights created by the Committee’s rules cannot be that illusory.
Of course, should Yellin have refused to answer in the mistaken but good-faith belief that his rights had been violated, his mistake of law would be no defense. Watkins v. United States, 354 U. S. 178,208; Sinclair v. United States, 279 U. S. 263, 299. But he would at least be entitled to submit the correctness of his belief to a-court of law.
Yellin should be permitted the same opportunity for judicial review when he discovers at trial that his rights have been violated. This is especially so when the Committee’s practice leads witnesses to misplaced reliance upon its rules. When reading a copy of the Committee’s rules, which must be distributed to every witness under Rule XVII, the witness’ reasonable expectation is that the Committee actually does what it purports to do, adhere to its own rules. To foreclose a defense based upon those rules, simply because the witness was deceived by the Committee’s appearance of regularity, is not fair. *124The Committee prepared the groundwork for prosecution in'Yellin’s case meticulously. It is not too exacting to require that the Committee be equally meticulous in obeying its own rules.
Reversed.
The constitutional questions upon which we need not pass are whether the Committee’s investigation infringed upon petitioner’s rights under the First Amendment and whether petitioner was convicted under an unconstitutionally vague statute. In addition, we do not discuss petitioner’s contention that the trial judge erred in excluding expert testimony about the factors which should be considered in determining petitioner’s rights under the First Amendment.
The Committee’s General Counsel had asked Mr. Yellin a few preliminary questions when Mr. Rabinowitz interrupted.
“Mr. Rabinowitz. Mr. Counsel [Mr. Tavenner], I wonder whether it would be possible to read into the record the exchange of telegrams between myself and the committee in connection with.the witness’s testimony. I would like to have it appear in the record.
“The Chairman. We will decide' whether it will be made á part of the record when the. executive session is Held. Go ahead.
“Mr. Rabinowitz. Mr. Chairman, I sent the telegrams because I wanted’them to appear. I do not care whether they appear publicly or not. I do want it to appear that that exchange of telegrams occurred. I did not do it just to increase the revenue of the telegram company.
“The Chairman. Well, whatever the reason was, whether it has been stated or otherwise, it will be considered in executive session.
“Mr. Rabinowitz. May I state—
Consider, for example, the following testimony of Congressman Walter:
“Q. [By Mr'. Rabinowitz] So that at the time I raised at this hearing the question of the telegrams, you didn’t know anything about any telegrams, and you weren’t sufficiently interested to find out what I wás talking about; is that right?
“A. [By Congressman Walter] Well, not exactly that, Mr. Rabinowitz. I was interested in knowing. I knew that you made an application for an executive session.
“Q. How did you know that?
“A. Well, the telegram; at least, that’s what you started to talk about.
“Q. You knew it at the time of the hearing?
“A. No. Isn’t that what you started to talk about?'
“Q. When did you first learn that I had made an application for aji executive session?
“A. 1 believe today. I never had seen these telegrams, actually. I heard you mention them, at least now my recollection is that I heard you mention them, but I haven’t seen them, until this minute.”
(Emphasis added.)
See also the following testimony:
“Q. [By Mr. Rabinowitz] Well, weren’t you interested in finding out what I was talking about?
“A. [By Congressman Walter] 1 knew what you were talking about. You were talking about a telegram that you say- you sent, and it was too late- then to raise any question that might have been raised by the telegram.”
Later Congressman Walter said:
“I'think the impression I got was that these were telegrams that were more or less in the nature of a request to postpone, without grounds, or whatever it was that Mr. Tavenner told me and the other members of the Committee; and I think that we were just not impressed by it.”
The following occurred during Mr. Rabinowitz’ direct examination of Congressman Walter:
“Q. Well, did you, or did you not, take it up in executive session as you said you would?
“A. I am not clear; I think that we probably did talk about making it a part of the record, and I think the conclusion was reached that it was not properly a part of the record already made.
“Q. Didn’t you testify, Congressman, just" a few minutes ago, while' you were on the stand, that the first you knew about the contents of the telegram was just now, when you got on the witness stand?
“A. That’s right.
“Q. So you discussed this-whole matter in executive session after the Gary hearings, without even knowing what the telegrams said?
“A. That’s about it.
“Q. And you reached the conclusion not to make them a part of the record without even knowing what was in them?
. “A. That’s right. ...”
Mr. Rabinowitz asked Congressman Walter:
“But it wasn’t worth the chance of calling him in executive session, to see what his position' would have been?
“A. I am sure that had you communicated this whole matter to the Committee before we left Washington so that we could have given it due consideration — we would have, and always do — we might have a different situation today.’’ (Emphasis added.)
Congressman Walter also said he was “sure this could not have happened, had you [Mr. Rabinowitz] addressed your telegram to me.”
Note also the following question by Mr. Rabinowitz and answer by Mr. Tavenner:
“Q. And does that rule [Rule IV] operate ever for the protection of a witness who is called?
“A. Certainly.”
Although, for reasons to be developed later, it does not appear that the Committee was following Rule IV in Yellin’s case, it seems clear that the Committee realized its public interrogation of Yellin would injure .his reputation. Congressman Walter testified, for example, that:
“A. . . . [T]he Committee already passed on thé question of whether or not we would hear Mr. Yellin at a session when the purpose of calling him was discussed, and it was decided then that the rule with respect to an executive session was not applicable because the investigator — and I might say it was Mr. Collins, a former F. B. I. agent, who developed this entire matter, and we were willing to accept his story with respect to the proposed testimony.
“Q. And what was his story?
“A. Well, his story was that the man was a known Communist; that he had been active in the international conspiracy, and that he had deceived his employer; and, furthermore, he came within the category of those people that we were experiencing a great deal of difficulty in finding out about with respect to the colonization.”
Mr. Tavenner also said he would not have recommended to the Committee that Yellin be heard in executive session “[bjecause we *118knew that he was a member of the Communist Party and he was in a position to , give the Committee information, if he wanted to.”
From the Committee’s knowledge, whether it be reliable or not, the Committee could only .have concluded' that Yellin’s reputation would suffer. Yet Congressman Walter said this was the kind of case in which a public hearing was appropriate.
Any suggestion that petitioner’s request was untimely cannot be accepted. For one thing, only 14 days intervened between-service of the subpoena upon petitioner and delivery of his request to the Committee’s offices in Washington. Also' it is of some significance that the Committee did not hold another witness at the Gary hearings, one Joseph Gyurko, to the strict standard of timeliness now urged. Gyurko had sent a telegram to the Committee’s offices in Washington about noon on Saturday, February 8, 1958. When Gyurko was called on Tuesday, February 11, he was given an executive hearing, even though Congressman Walter expressed the opinion that Gyurko had deliberately waited until after business hours on Saturday to send his request. Since the Committee did not evenhandedly deny executive sessions to all who made such eleventh hour requests, it is not in a fair position to plead the untimeliness of Yellin’s request.
Although, as a matter of due process, a witness is entitled to an explanation of the pertinency of a question, if he asks for it, it appears he may lose that right if he fails to make a timely objection. See Deutch v. United States, 367 U. S. 45.6, 468-469; Barenblatt v. United States, 360 U. S. 109, 123-124; Watkins v. United States, 354 U. S. 178, 214-215.
For other instances in which a witness’ defense has been rejected because he failed to make timely objection, see McPhaul v. United States, 364 U. S. 372, 379; United States v. Bryan, 339 U. S. 323, 332-333; Hartman v. United States, 290 F. 2d 460, 467.