Some people are hostile to the Fifth Amendment’s provision unequivocally commanding that no United States *376official shall compel a person to be a witness against himself. They consider the provision as an outmoded relic of past fears generated by ancient inquisitorial practices that could not possibly happen here. For this reason the privilege to be silent is sometimes accepted as being more or less of a constitutional nuisance which the courts should abate whenever and however possible. Such an end could be achieved by two obvious judicial techniques: (1) narrow construction of the scope of the privilege; (2) broad construction of the doctrine of “waiver.” Any attempt to use the first of these methods, however, runs afoul of approximately 150 years of precedent. See Patricia Blau v. United States, 340 U. S. 159, and cases there cited. This Court has almost always construed the Amendment broadly1 on the view that compelling a person to convict himself of crime is “contrary to the principles of a free government” and “abhorrent to the instincts of an American”; that while such a coercive practice “may suit the purposes of despotic power ... it cannot abide the pure atmosphere of political liberty and personal freedom,” Boyd v. United States, 116 U. S. 616, 632; but cf. United States v. Murdock, 284 U. S. 141.

The doctrine of waiver seems to be a more palatable but equally effective device for whittling away the protection afforded by the privilege, although I think today’s application of that doctrine cannot be supported by our past decisions. Of course, it has never been doubted that *377a constitutional right could be intentionally relinquished and that such an intention might be found from a “course of conduct.” Shepard v. Barron, 194 U. S. 553, 568. But we have said that intention to waive the privilege against self-incrimination is not “lightly to be inferred” and that vague and uncertain evidence will not support a finding of waiver. Smith v. United States, 337 U. S. 137, 150, relying on Johnson v. Zerbst, 304 U. S. 458, 464, and cases there cited. In the case of this petitioner, there is no evidence that she intended to give up her privilege of silence concerning the persons in possession of the Communist Party records. To the contrary, the record — as set out in the Court’s opinion — shows she intended to avoid answering the question on whatever ground might be available and asserted the privilege against self-incrimination at the first moment she became aware of its existence.2 This fact and the cases which make it crucial are ignored in the decision today.

Apparently, the Court’s holding is that at some uncertain point in petitioner’s testimony, regardless of her intention, admission of associations with the Communist Party automatically effected a “waiver” of her constitutional protection as to all related questions.3 To adopt such a rule for the privilege against self-incrimination, *378when other constitutional safeguards must be knowingly-waived, relegates the Fifth Amendment’s privilege to a second-rate position. Moreover, today’s holding creates this dilemma for witnesses: On the one hand, they risk imprisonment for contempt by asserting the privilege prematurely; on the other, they might lose the privilege if they answer a single question. The Court’s view makes the protection depend on timing so refined that lawyers, let alone laymen, will have difficulty in knowing when to claim it.4 In this very case, it never occurred to the trial judge that petitioner waived anything.5 And even if voluntary testimony can under some circumstances work a waiver, it did not do so here because what petitioner stated to the grand jury “standing alone did not amount to an admission of guilt or furnish clear proof of crime . . . .” Arndstein v. McCarthy, 254 U. S. 71, 72.6

*379Furthermore, unlike the Court, I believe that the question which petitioner refused to answer did call for additional incriminating information. She was asked the names of the persons to whom she had turned over the Communist Party books and records. Her answer would not only have been relevant in any future prosecution of petitioner for violation of the Smith Act but also her conviction might depend on testimony of the witnesses she was thus asked to identify. For these reasons the question sought a disclosure which would have been incriminating to the highest degree. Certainly no one can say that the answer “[could not] possibly be used as a basis for, or in aid of, a criminal prosecution against the witness . . . .” Brown v. Walker, 161 U. S. 591, 597.7

The records in this and in the companion cases8 reveal a flagrant disregard of the constitutional privileges of petitioner and others called before the grand jury. The Special United States Attorney in charge made unwar*380ranted assurances that might well have misled witnesses unable to match legal wits with him into making self-incriminating admissions.9 Although petitioner had been allowed on a previous day to consult with counsel, at the time she was brought before the District Court for final consideration of her case the judge arbitrarily refused to permit counsel to speak in her behalf, summarily commanding the attorney to sit down, and almost immediately thereafter sentenced petitioner to four months’ imprisonment.10 In convicting her, the district judge neither held nor intimated that the privilege against self-incrimination had been waived.11 His erroneous belief was that intimate association with the Communist Party was not an incriminating fact. Therefore, although the Court now describes petitioner’s claim of privilege as *381an “afterthought/’ it seems to me that the real “afterthought” in this case is the affirmance of the judgment below on a “waiver” or equivalent theory. More important, however, I believe that today’s expansion of the “waiver” doctrine improperly limits one of the Fifth Amendment’s great safeguards.12

I would reverse the judgment of conviction.

APPENDIX TO OPINION OF MR. JUSTICE BLACK.

The following is the full transcript of proceedings at the time the judgment now under review was entered:

“The Court: . . . What is the next case? Can we dispose of these ladies now?

“Mr. Goldschein [Special United States Attorney]: Mrs. Jane Rogers.

“The Court: Is she here ?

“Mr. Goldschein: She is here, yes, sir. Now, may it please Your Honor—

“The Court: Step over here, madam. What is the status of her case?

“Mr. Goldschein: Mrs. Rogers refuses to answer the questions propounded to her in the grand jury room. She was brought back on yesterday, but says that she will answer one question but will not answer any others, and was advised that it would be necessary for her to answer all questions propounded except those which would incriminate her for the violation of a federal offense, and she says she won’t answer any.

“The Court: Is that your position, madam?

“Mr. Menin [counsel for petitioner]: I think there has been a misunderstanding.

*382“The Court: Just a minute. Will you please be seated, Mr. Menin? Please be seated.

“Mr. Menin: Well, I represent this lady.

“The Court: Just a moment. Please be seated.

“Mr. Menin: Very well.

“The Court: I’ll hear you in due course[.] Madam, do you still persist in not answering these questions?

“Mrs. Rogers: Well, on the basis of Mr. Menin’s statements this morning—

“The Court: Will you please answer the question yes or no?

“Mrs. Rogers: Well, I think that’s rather undemocratic [.] I’m a very honest person. Would you mind letting me consider—

“The Court: Make any statement you wish.

“Mrs. Rogers: Well, as I said before, I’m a very honest person and I’m not acquainted with the tricks of legal procedure, but I understand from the reading of these cases this morning that I am — and I do have a right to refuse to answer these questions, on the basis that they would tend to incriminate me, and you read it yourself, that I have a right to decide that.

“The Court: You have not the right to say.

“Mrs. Rogers: According to what you read, I do. I stand on that.

“The Court: All right. If you will make no changes, it is the judgment and sentence of the court you be confined to the custody of the Attorney General for four months. Call the next case.” Transcript of Record, pp. 76-78 (September 23, 1948).

delivered the opinion of the Court.

This case arises out of an investigation by the regularly convened grand jury of the United States District Court for the District of Colorado. The books and records of the Communist Party of Denver were sought as necessary to that inquiry and were the subject of questioning by the grand jury. In September, 1948, petitioner, in response to a subpoena, appeared before the grand jury. She testified that she held the position of Treasurer of the Communist Party of Denver until January, 1948, and that, by virtue of her office, she had been in possession of membership lists and dues records of the Party. Petitioner denied having possession of the records and testified that she had turned them over to another. But she refused to identify the person to whom she had given the Party’s books, stating to the court as her only reason: “I don’t feel that I should subject a person or persons to the same thing that I’m going through.”1 The court thereupon committed petitioner to the custody of the marshal *369until ten o’clock the next morning, expressly advising petitioner of her right to consult with counsel.2

The next day, counsel for petitioner informed the court that he had read the transcript of the prior day’s proceedings and that, upon his advice, petitioner would answer the questions to purge herself of contempt.3 However, *370upon reappearing before the grand jury, petitioner again refused to answer the question. The following day she was again brought into court. Called before the district judge immediately after he had heard oral argument concerning the privilege against self-incrimination in another case, petitioner repeated her refusal to answer the question, asserting this time the privilege against self-incrimination.4 After ruling that her refusal was not privileged, the district judge imposed a sentence of four months for contempt. The Court of Appeals for the Tenth Circuit affirmed, 179 F. 2d 559 (1950), and we granted certiorari, 339 U. S. 956 (1950).

If petitioner desired the protection of the privilege against self-incrimination, she was required to claim it. *371United States v. Monia, 317 U. S. 424, 427 (1943). The privilege "is deemed waived unless invoked.” United States v. Murdock, 284 U. S. 141, 148 (1931).5 Furthermore, the decisions of this Court are explicit in holding that the privilege against self-incrimination “is solely for the benefit, of the witness,”6 and “is purely a personal privilege of the witness.”7 Petitioner expressly placed her original declination to answer on an untenable ground, since a refusal to answer cannot be justified by a desire to protect others from punishment,8 much less to protect another from interrogation by a grand jury. Petitioner’s claim of the privilege against self-incrimination was pure afterthought. Although the claim was made at the time of her second refusal to answer in the presence of the court, it came only after she had voluntarily testified to her status as an officer of the Communist Party of Denver. To uphold a claim of privilege in this case would open the way to distortion of facts by permitting a witness to select any stopping place in the testimony.

The privilege against self-incrimination, even if claimed at the time the question as to the name of the person to whom petitioner turned over the Party records was asked, would not justify her refusal to answer. As a preliminary matter, we note that petitioner had no privilege with respect to the books of the Party, whether it *372be a corporation9 or an unincorporated association.10 Books and records kept “in a representative rather than in a personal capacity cannot be the subject of the personal privilege against self-incrimination, even though production of the papers might tend to incriminate [their keeper] personally.” United States v. White, 322 U. S. 694, 699 (1944).11 Since petitioner’s claim of privilege cannot be asserted in relation to the books and records sought by the grand jury, the only claim for reversal of her conviction rests on the ground that mere disclosure of the name of the recipient of the books tends to incriminate.

In Patricia Blau v. United States, 340 U. S. 159 (1950), we held that questions as to connections with the Communist Party are subject to the privilege against self-incrimination as calling for disclosure of facts tending to criminate under the Smith Act.12 But petitioner’s conviction stands on an entirely different footing, for she had freely described her membership, activities and office in the Party. Since the privilege against self-incrimination *373presupposes a real danger of legal detriment arising from the disclosure, petitioner cannot invoke the privilege where response to the specific question in issue here would not further incriminate her. Disclosure of a fact waives the privilege as to details. As this Court stated in Brown v. Walker, 161 U. S. 591, 597 (1896):

“Thus, if the witness himself elects to waive his privilege, as he may doubtless do, since the privilege is for his protection and not for that of other parties, and discloses his criminal connections, he is not permitted to stop, but must go on and make a full disclosure."13

Following this rule, federal courts have uniformly held that, where criminating facts have been voluntarily revealed, the privilege cannot be invoked to avoid disclosure of the details.14 The decisions of this Court in Arndstein v. McCarthy, 254 U. S. 71 (1920), and McCarthy v. Arndstein, 262 U. S. 355 (1923), further support the conviction in this case for, in sustaining the privilege on each appeal, the Court stressed the absence of any previous “admission of guilt or incriminating facts,”15 and relied particularly upon Brown v. Walker, supra, and Foster v. People, 18 Mich. 266 (1869). The holding of the Michigan court is entirely apposite here:

“[WJhere a witness has voluntarily answered as to materially criminating facts, it is held with uniformity *374that he cannot then stop short and refuse further explanation, but must disclose fully what he has attempted to relate.” 18 Mich, at 276.16

Requiring full disclosure of details after a witness freely testifies as to a criminating fact does not rest upon a further “waiver” of the privilege against self-incrimination. Admittedly, petitioner had already “waived” her privilege of silence when she freely answered criminating questions relating to her connection with the Communist Party. But when petitioner was asked to furnish the name of the person to whom she turned over Party records, the court was required to determine, as it must whenever the privilege 'is claimed, whether the question presented a reasonable danger of further crimination in light of all the circumstances, including any previous disclosures. As to each question to which a claim of privilege is directed, the court must determine whether the answer to that particular question would subject the witness to a “real danger” of further crimination.17 After petitioner’s admission that she held the office of Treasurer of the Communist Party of Denver, disclosure of acquaintance with her successor presents no more than *375a “mere imaginary possibility”18 of increasing the danger of prosecution.19

Petitioner’s contention in the Court of Appeals and in this Court has been that, conceding her prior voluntary crimination as to one element of proof of a Smith Act violation, disclosure of the name of the recipient of the Party records would tend to incriminate as to the different crime of conspiracy to violate the Smith Act. Our opinion in Patricia Blau v. United States, supra, at 161, explicitly rejects petitioner’s argument for reversal here in its holding that questions relating to activities in the Communist Party are criminating both as to “violation of (or conspiracy to violate) the Smith Act.” Of course, at least two persons are required to constitute a conspiracy, but the identity of the other members of the conspiracy is not needed, inasmuch as one person can be convicted of conspiring with persons whose names are unknown.20

Affirmed.