with whom Justice Brennan and Justice Blackmun join, dissenting.
I agree with much in Justice Stevens’ dissent, post, at 96-98. Whether a particular fact is an element of a criminal offense that, under In re Winship, 397 U. S. 358 (1970), must be proved by the prosecution beyond a reasonable doubt is a question that must be decided by this Court and cannot be abdicated to the States. “[I]f Winship were limited to those facts that constitute a crime as defined by state law, a State could undermine many of the interests that decision sought to protect without effecting any substantive change in its law.” Mullaney v. Wilbur, 421 U. S. 684, 698 (1975). The deference that the majority gives to the Pennsylvania Legislature’s statement that the visible possession of a firearm should not be considered an element of the crime defined by 42 Pa. Cons. Stat. § 9712 (1982) is thus wholly inappropriate.
*94I would not, however, rely in this case on the formalistic distinction between aggravating and mitigating facts. The “continued functioning of the democratic process,” post, at 100 (Stevens, J., dissenting), might provide us with some assurance that States will not circumvent the guarantee of Winship by criminalizing seemingly innocuous conduct and then placing the burden on the defendant to establish an affirmative defense. But this Court nonetheless must remain ready to enforce that guarantee should the State, by placing upon the defendant the burden of proving certain mitigating facts, effectively lighten the constitutional burden of the prosecution with respect to the elements of the crime. See Patterson v. New York, 432 U. S. 197, 206-207 (1977) (allowing State to require defendant to prove extreme emotional disturbance by preponderance of the evidence but noting that this affirmative defense “does not serve to negative any facts of the crime which the State is to prove in order to convict of murder”).
I would put off until next Term any discussion of how mitigating facts should be analyzed under Winship. This issue will be aired when the Court considers Martin v. Ohio, No. 85-6461, cert. granted, 475 U. S. 1119 (1986), in which a defendant challenges Ohio’s requirement that the accused bear the burden of proving a claim of self-defense by a preponderance of the evidence. For now, it is enough to agree with Justice Stevens that “if a State provides that a specific component of a prohibited transaction shall give rise both to a special stigma and to a special punishment, that component must be treated as a ‘fact necessary to constitute the crime’ within the meaning of our holding in In re Winship,” post, at 103. Pennsylvania has attached just such consequences to a finding that a defendant “visibly possessed a firearm” during the commission of any aggravated assault, and, under Winship, the prosecution should not be relieved of proving that fact beyond a reasonable doubt. I dissent.