concurring in the judgment.
There is no statutory authority for a Government appeal from a judgment of acquittal in a criminal case. The plain language of 18 U. S. C. § 3731, together with its unambiguous legislative history, makes it perfectly clear that Congress did not authorize—and did not intend to authorize—appeals from acquittals.1
*577Prior to its most recent amendment in 1970, the Criminal Appeals Act had been a source of great confusion, “a most unruly child that has not improved with age,” United States v. Sisson, 399 U. S. 267, 307. The Act had been construed to incorporate obscure distinctions between various types of dismissals, some of which were appealable directly to this Court, some to the court of appeals, and some that could not be appealed to either court.2 However, the one thing that had always been clear was that “no appeal [could] be taken by the Government from an acquittal no matter how erroneous the legal theory underlying the decision,” id., at 299.
The 1970 amendment changed the law by eliminating all distinctions between different kinds of dismissals, but neither the present statute nor any of its predecessors has ever authorized an appeal from an acquittal. The statute, in relevant part, now reads:
“In a criminal case an appeal by the United States shall lie to a court of appeals from a decision, judgment, or order of a district court dismissing an indictment or information as to any one or more counts, except that no appeal shall lie where the double jeopardy clause of the United States Constitution prohibits further prosecution.” 18 U. S. C. § 3731 (emphasis added).
*578There is nothing in this statutory language to suggest that a judgment of acquittal, as opposed to a dismissal, is appealable.
The legislative history demonstrates that Congress intended to eliminate nonconstitutional barriers to appeals from dismissals, but did not intend to allow appeals from acquittals. As this Court has recognized, the Senate Report is the key to the legislative history.3 The Report opens by describing the purpose of the bill as being “to resolve serious problems which frequently have arisen with respect to the right of the United States to appeal rulings which terminate prosecutions other than by judgments of acquittal . . .” S. Rep. No. 91-1296, p. 2 (1970) (emphasis added). Apart from the problem of direct Supreme Court review, the Report states that the “major problem that has arisen under the present statute concerns the total lack of appealability of certain kinds of dismissals and suppressions.” Id., at 4 (emphasis added). The Report then discusses at length the then-existing limitations on appeals from dismissals.4 The Committee believed *579that the Constitution allowed the Government to appeal any dismissal, id., at 7-12, and stated that the bill was “intended to be liberally construed so as to effectuate its purpose of permitting the Government to appeal from dismissals of criminal prosecutions by district courts in all cases where the Constitution permits . . . Id., at 18 (emphasis added). On the other hand, the Committee believed that the Constitution barred any appeal from an acquittal or from a dismissal amounting to an acquittal; “[a] true acquittal is based upon the insufficiency of the evidence to prove an element of the offense.” Id., at 11.
The same understanding was demonstrated by the bill’s sponsor when he presented the Senate Report on the floor. He summarized the bill as providing that “the Government has the right to appeal any ruling by a district court in a criminal case which dismisses a prosecution in favor of a defendant except where the ruling is an acquittal”; he also presented a letter from the Solicitor General explaining that the bill would allow “an appeal from any dismissal except one amounting to a 'judgment of acquittal,' i. e., a factual judgment that the defendant is not guilty of the crime charged and is thereby entitled to protection against double jeopardy.” 116 Cong. Rec. 35659 (1970) (remarks of Sen. Hruska).
*580As the Court explained in Wilson, the Conference Committee made a minor change in the wording of the bill. See Wilson, 420 U. S., at 338. That change narrowed the bill in two respects. The Senate bill had allowed appeals from dismissals and also from any order “terminating a prosecution in favor of a defendant,” and had expressly barred appeals from a judgment of acquittal.5 In short, as the Conference Committee stated, the Senate bill authorized an appeal from “any decision or order terminating a prosecution except an acquittal,” H. R. Conf. Rep. No. 91-1768, p. 21 (1970). The Conference Committee’s change narrowed the bill by deleting the reference to orders “terminating a prosecution in favor of a defendant,” leaving only dismissals appealable. (This deletion rendered superfluous the exception for acquittals, which was also deleted.) The Committee’s change also narrowed the bill by barring any appeal, even from a dismissal, when further prosecution would violate double jeopardy.
An attempt to authorize the Government to appeal from acquittals would have represented a radical change in the law. The sponsor of the bill apparently did not understand the legislation to have such far-reaching effects; he described it as “noncontroversial legislation which would do away with unnecessary and perplexing jurisdictional problems in appeals by the Government in criminal cases . . . .” 116 Cong. Rec. 35659 (1970) (remarks of Sen. Hruska). Similarly, the Conference Report describes the Senate bill as merely eliminating “[t]echnical distinctions . . . on appeals by the United States,” H. R. Conf. Rep. No. 91-1768, supra, at 21.6
*581Interpreting legislative history is sometimes a perplexing and uncertain task. In this instance, however, the legislative history is absolutely clear: Congress was interested solely in expanding the Government's right to appeal from the dismissal of an indictment; it had no desire to allow appeals from acquittals and believed such appeals would be unconstitutional.
Since I am satisfied that Congress has not authorized the Government to appeal from a judgment of acquittal, the only question presented is whether such a judgment was entered in this case. The answer to that question, as the Court demonstrates, is perfectly clear. By virtue of Fed. Rule Crim. Proc. 29 (c), the mistrial did not terminate the judge’s power to make a decision on the merits. His ruling, in substance as well as form, was therefore an acquittal.7 For this reason, I concur in the Court’s judgment.
The contrary dictum in United States v. Wilson, 420 U. S. 332, 336-339; United States v. Jenkins, 420 U. S. 358, 363-364; Serfass v. United States, 420 U. S. 377, 383-387, is not controlling for these reasons: First, the statutory issue was not in dispute in any of those cases. Two of the defendants expressly conceded the applicability of the statute in their cases, Brief for Respondent in United States v. Wilson, O. T. 1974, No. 73-1395, p. 2; Brief for Respondent in United States v. Jenkins, O. T. 1974, No. 73-1513, p. 10. The third defendant simply failed to address the statutory issue, see Brief for Petitioner in Serfass v. United States, O. T. 1974, No. 73-1424, probably because his case involved a pretrial dismissal of the indictment. Hence, the Court was unaided by an adversary presentation of the issue. Moreover, re-examination of the language used in the decisions would not undermine their holdings. The two cases in which the Court upheld the Government appeal clearly did not involve acquittals on the merits. (Serfass was a pretrial dismissal; Wilson was a dismissal on speedy trial grounds.) The third case, Jenkins, *577arguably involved an acquittal, but the Court held on constitutional grounds that the appeal was barred.
Second, as I indicate in the text, infra, at 581, it is perfectly clear that the dictum is incorrect. In view of our special responsibility for supervising the proper functioning of the federal criminal justice system, we should not hesitate to correct a plain mistake involving a technical problem of procedure when there has been no prejudicial reliance on that mistake.
The difficulty of the problems presented by the statute is illustrated by the sharply divided conclusions reached in the various opinions in cases such as United States v. Sisson, 399 U. S. 267; United States v. Ponto, 454 F. 2d 657 (CA7 1971) (en banc); United States v. Apex Distributing Co., 270 F. 2d 747 (CA9 1959) (en banc).
The significance of this Senate Report in understanding the Act was well expressed in Serfass v. United States, supra, at 387 n. 10:
“The relevance and significance of the ‘well considered and carefully prepared’ report of the Senate Judiciary Committee, see Schwegmann Bros. v. Calvert Distillers Corp., 341 U. S. 384, 395 (1951) (Jackson, J., concurring), is not affected by the fact that the amendments proposed by the Committee and adopted without change by the Senate were modified by the House-Senate Conference Committee. See H. R. Conf. Rep. No. 91-1768, p. 21 (1970). The latter report contains no explanation of the changes made, and the changes themselves are consistent with the intent expressed in the Senate Report. See United States v. Wilson, ante, at 337-339.”
Subsection A is entitled “The Nature of the District Court Decision as a Limitation on Appeals from Dismissals,” and begins with the statement that “[t]he now-archaic terminology employed in the original statute . . . unnecessarily precludes the Government from appealing many dismissals of prosecutions.” S. Rep. No. 91-1296, at 5. The Report then states that the current Act “does not provide for an appeal by the United States to any court in a large variety of cases where the dismissal is based *579on grounds having nothing to do with any defect in the indictment, or the construction or invalidity of the underlying statute.” Ibid. The Report gives as examples dismissals for failure of the prosecution to comply with discovery or for lack of timely prosecution. The Report then refers to the use of old common-law terms like “ 'judgment sustaining a motion in bar,' ” giving rise to problems like that which the Court confronted in United States v. Sisson, supra. S. Rep. No. 91-1296, p. 6.
Subpart B of the Senate Report deals with “The Attachment of Jeopardy as a Limitation on Appeals from Dismissals.” This section was concerned with appeal of “a decision sustaining a motion in bar after jeopardy has attached,” ibid. Congress was concerned that a defendant could reserve issues of law until the trial and then preclude any possible review. Id., at 7. An example was a case in which the trial judge ruled the Selective Service Act unconstitutional during the trial. Id., at 11.
The bill provided that an appeal would lie “from a decision, judgment or order of a district court dismissing an indictment or information or terminating a prosecution in favor of a defendant as to one or more counts, except that no appeal shall lie from a judgment of acquittal.” S. 3132.
When the Conference bill was reported back to both Houses, its provision on appeals was described in cautious terms hardly appropriate to a proposal to go to the constitutional limits: in the Senate, as “authoriz[ing] *581appeals in certain classes of criminal cases,” 116 Cong. Rec. 42147 (1970) (remarks of Sen. McClellan) (emphasis added); in the House, as an amendment “to broaden and clarify the right of the Government to appeal dismissals of criminal cases,” id., at 42197 (remarks of Rep. Celler).
As we pointed out in United States v. Sanford, 429 U. S. 14, the mistrial in that case was entirely different because the proceedings in the trial court terminated without any decision on the merits.
“The trial of respondents on the indictment terminated, not in their favor, but in a mistrial declared, sua sponte, by the District Court. Where the trial is terminated in this manner, the classical test for determining whether the defendants may be retried without violating the Double Jeopardy Clause is stated in Mr. Justice Story’s opinion for this Court in United States v. Perez, 9 Wheat. 579, 580 (1824):
“ ‘We are of opinion, that the facts constitute no legal bar to a future trial. The prisoner has not been convicted or acquitted, and may again be put upon his defence. . .' " Id., at 15.