with whom Mr. Justice Brennan joins, concurring in the judgment.
I agree with the Court that petitioner, having made incriminating disclosures on his income tax returns rather than having claimed the privilege against self-incrimination, cannot thereafter assert the privilege to bar the introduction of his returns in a criminal prosecution. I disagree, however, with the Court’s rationale, which is far broader than is either necessary or appropriate to dispose of this case.
This case ultimately turns on a simple question— whether the possibility of being prosecuted under 26 U. S. C. § 7203 for failure to make a return compels a taxpayer to make an incriminating disclosure rather than claim the privilege against self-incrimination on his return. In discussing this question, the Court notes that only a “willful” failure to make a return is punishable under § 7203, and that “a defendant could not properly be convicted for an erroneous claim of privilege asserted in good faith.” Ante, at 663 n. 18. Since a good-faith .erroneous assertion of the privilege does not expose a taxpayer to criminal liability, I would hold that the threat of prosecution does not compel incriminating disclosures in violation of the Fifth Amendment. The protection accorded a good-faith assertion of the privilege effectively preserves the taxpayer’s freedom to choose between making incriminating disclosures and claiming his Fifth Amendment privilege, and I would affirm the judgment of the Court of Appeals for that reason.
Not content to rest its decision on that ground, the Court decides that even if a good-faith erroneous assertion of the privilege could form the basis for criminal *667liability, the threat of prosecution does not amount to compulsion. It is constitutionally sufficient, according to the Court, that a valid claim of privilege is a defense to a § 7203 prosecution. Ante, at 662-665. In so holding, the Court answers a question that by its own admission is not presented by the facts of this case. And, contrary to the implication contained in the Court’s opinion, the question is one of first impression in this Court.
Citing United States v. Murdock, 284 U. S. 141 (1931) (Murdock I), the Court observes that a taxpayer who claims the privilege on his return can be convicted of a § 7203 violation without having been given a preliminary ruling on the validity of his claim and a "second chance” to complete his return after his claim is rejected. The Court then leaps to the conclusion that the Fifth Amendment is satisfied as long as a valid claim of privilege is a defense to a § 7203 prosecution.
I accept the proposition that a preliminary ruling is not a prerequisite to a § 7203 prosecution. But cf. Quinn v. United States, 349 U. S. 155, 165-170 (1955). But it does not follow, and Murdock I does not hold, that the absence of a preliminary ruling is of no import in considering whether a defense of good-faith assertion of the privilege is constitutionally required.* It is one thing to deny a good-faith defense to a witness who is given a prompt ruling on the validity of his claim of privilege and an opportunity to reconsider his refusal to testify before subjecting himself to possible punishment for contempt. See, e. g., Maness v. Meyers, 419 U. S. 449, 460-461 (1975). It would be quite another to deny a good-faith defense to someone like petitioner, who may *668be denied a ruling on the validity of his claim of privilege until his criminal prosecution, when it is too late to reconsider. If, contrary to the undisputed fact, a taxpayer had no assurance of either a preliminary ruling or a defense of good-faith assertion of the privilege, he could claim the privilege only at the risk that an erroneous assessment of the law of self-incrimination would subject him to criminal liability. In that event, I would consider the taxpayer to have been denied the free choice to claim the privilege, and would view any incriminating disclosures on his tax return as “compelled” within the meaning of the Fifth Amendment. Only because a good-faith erroneous claim of privilege entitles a taxpayer to acquittal under § 7203 can I conclude that petitioner's disclosures are admissible against him.
Indeed, as the Court notes, ante, at 663 n. 18, the Court held that Murdock was entitled to acquittal if his assertion of the privilege was in good faith. United, States v. Murdock, 290 U. S. 389 (1933) (Murdock II).