whom
Mr. Justice Burton joins, concurring in the result.This case involves a native-born citizen of Japanese parentage who has been declared to have lost his citizenship by virtue of § 401 (c) of the Nationality Act of 1940, *14054 Stat. 1137, 1169, for having served in the Japanese armed forces while subject to the law of Japan making failure to serve a crime. That is the case before the Court. The defined issue raised by this case is the only issue, in my judgment, that the Court should decide.
Petitioner asserts that his service in the Japanese forces was performed under duress. His claim of duress is based on the fact that he was inducted into the Japanese armed forces pursuant to the compulsory conscription law of that country,1 and that rumors of harsh punishment of draft evaders by the secret police and the ruthlessness of the government in power made him afraid to take any action to avoid service. The evidence to rebut this testimony, elicited on cross-examination, was that he had failed to take certain actions to avoid service; the only affirmative act urged in support of the voluntariness of his entry into service is that he went to Japan when he was of draft-eligible age2 and remained there until inducted.
It is common ground that conduct will result in expatriation only if voluntarily performed. See Mackenzie v. Hare, 239 U. S. 299, 311-312; cf. Acheson v. Okimura, 342 U. S. 899; Acheson v. Murata, 342 U. S. 900. Accordingly, where a person who has been declared expatriated contests that declaration on grounds of duress, the evidence in support of this claim must be sympathetically scrutinized. This is so both because of the extreme gravity of being denationalized and because of the subtle, psychologic factors that bear on duress.
*141The issue that is ultimately decisive in a litigation is one thing, the mode for determining it quite another. The fact that conduct, in order to result in loss of citizenship, must be voluntary behavior does not inherently define the appropriate manner of its proof. The Government properly has a very heavy burden in expatriation cases: it must establish that the citizen committed an “act of expatriation” — i. e., engaged in conduct of which the consequence is loss of citizenship — by clear, convincing and unequivocal evidence. Gonzales v. Landon, 350 U. S. 920, adopting the standard of Schneiderman v. United States, 320 U. S. 118, and Baumgartner v. United States, 322 U. S. 665. This is incumbent on the Government although the evidence in cases such as these may well be difficult to obtain. Much more difficult would it be for the Government to establish the citizen’s state of mind as it bears on his will, purpose and choice of action— in short, “voluntariness.” According to the ordinarily controlling principles of evidence, this would suggest that the individual, who is peculiarly equipped to clarify an ambiguity in the meaning of outward events, should have the burden of proving what his state of mind was. See Selma, Rome & Dalton R. Co. v. United States, 139 U. S. 560, 567-568. Moreover, any other evidence of his state of mind, outside of his own mental disclosures, will often be found only abroad, where the Government may have no facilities for conducting the necessary investigation. The Court should hesitate long before imposing on the Government, by a generalized, uncritical formula, a burden so heavy that the will of Congress becomes incapable of sensible, rational, fair enforcement.
Where an individual engages in conduct by command of a penal statute of another country to whose laws he is subject, the gravest doubt is cast on the applicability of the normal assumption — even in a prosecution for murder (see Leland v. Oregon, 343 U. S. 790) — that what *142a person does, he does of his own free will. When a consequence as drastic as denationalization may be the effect of such conduct, it is not inappropriate that the Government should be charged with proving that the citizen’s conduct was a response, not to the command of the statute, but to his own direction. The ready provability of the critical fact — existence of an applicable law, particularly a criminal law, commanding the act in question — provides protection against shifting this burden to the Government on the basis of a frivolous assertion of the defense of duress. Accordingly, the Government should, under the circumstances of this case, have the burden of proving by clear, convincing and unequivocal evidence that the citizen voluntarily performed an act causing expatriation.
Since the courts below were not guided by this formulation, the judgment should not be allowed to stand. However, the Government should not be denied a further opportunity to bring forward the necessary proof if it is able to do so. Whether, in other classes of cases in which the defense of duress is asserted, the Government should have the burden of proving its absence is a question the Court need not — and, therefore, should not — reach. For that reason, I concur in the result announced but cannot join the opinion of the Court.
According to a stipulation of the parties in the record, the Military Service Law of Japan provided punishment of up to three years of penal servitude for persons evading military service.
There does not seem to be any explicit basis in the record for the trial court’s finding (Finding of Fact No. Ill) that petitioner made the trip to Japan “knowing at that time that he was likely to be called for military service in the Japanese Armed Forces.”