with whom Justice Brennan and Justice Marshall join, and with whom Justice Blackmun joins with respect to Parts I and III, dissenting.
Today the Court holds that a defendant can be convicted of aggravated murder even though the jury may have a reasonable doubt whether the accused acted in self-defense, and thus whether he is guilty of a crime. Because I think this decision is inconsistent with both precedent and fundamental fairness, I dissent.
I
Petitioner Earline Martin was tried in state court for the aggravated murder of her husband. Under Ohio law, the elements of the crime are that the defendant has purposely killed another with “prior calculation and design.” Ohio Rev. Code Ann. §2903.01 (1982). Martin admitted that she *237shot her husband, but claimed that she acted in self-defense. Because self-defense is classified as an “affirmative” defense in Ohio, the jury was instructed that Martin had the burden of proving her claim by a preponderance of the evidence. Martin apparently failed to carry this burden, and the jury found her guilty.
The Ohio Supreme Court upheld the conviction, relying in part on this Court’s opinion in Patterson v. New York, 432 U. S. 197 (1977). The Court today also relies on the Patterson reasoning in affirming the Ohio decision. If one accepts Patterson as the proper method of analysis for this case, I believe that the Court’s opinion ignores its central meaning.
In Patterson, the Court upheld a state statute that shifted the burden of proof for an affirmative defense to the accused. New York law required the prosecutor to prove all of the statutorily defined elements of murder beyond a reasonable doubt, but permitted a defendant to reduce the charge to manslaughter by showing that he acted while suffering an “extreme emotional disturbance.” See N. Y. Penal Law §§125.25, 125.20 (McKinney 1975 and Supp. 1987). The Court found that this burden shifting did not violate due process, largely because the affirmative defense did “not serve to negative any facts of the crime which the State is to prove in order to convict of murder.” 432 U. S., at 207. The clear implication of this ruling is that when an affirmative defense does negate an element of the crime, the state may not shift the burden. See White v. Arn, 788 F. 2d 338, 344-345 (CA6 1986). In such a case, In re Winship, 397 U. S. 358 (1970), requires the state to prove the nonexistence of the defense beyond a reasonable doubt.
The reason for treating a defense that negates an element of the crime differently from other affirmative defenses is plain. If the jury is told that the prosecution has the burden of proving all the elements of a crime, but then also is in*238structed that the defendant has the burden of disproving one of those same elements, there is a danger that the jurors will resolve the inconsistency in a way that lessens the presumption of innocence. For example, the jury might reasonably believe that by raising the defense, the accused has assumed the ultimate burden of proving that particular element. Or, it might reconcile the instructions simply by balancing the evidence that supports the prosecutor’s case against the evidence supporting the affirmative defense, and conclude that the state has satisfied its burden if the prosecution’s version is more persuasive. In either case, the jury is given the unmistakable but erroneous impression that the defendant shares the risk of nonpersuasion as to a fact necessary for conviction.1
Given these principles, the Court’s reliance on Patterson is puzzling. Under Ohio law, the element of “prior calculation and design” is satisfied only when the accused has engaged in a “definite process of reasoning in advance of the killing,” i. e., when he has given the plan at least some “studied consideration.” App. 14 (jury instructions) (emphasis added). In contrast, when a defendant such as Martin raises a claim of *239self-defense, the jury also is instructed that the accused must prove that she “had an honest belief that she was in imminent danger of death or great bodily harm.”2 Id., at 19 (emphasis added). In many cases, a defendant who finds himself in immediate danger and reacts with deadly force will not have formed a prior intent to kill. The Court recognizes this when it states:
“It may be that most encounters in which self-defense is claimed arise suddenly and involve no prior plan or specific purpose to take life. In those cases, evidence offered to support the defense may negate a purposeful killing by prior calculation and design . . . .” Ante, at 234.
Under Patterson, this conclusion should suggest that Ohio is precluded from shifting the burden as to self-defense. The Court nevertheless concludes that Martin was properly required to prove self-defense, simply because “Ohio does not shift to the defendant the burden of disproving any element of the state’s case.” Ibid.
The Court gives no explanation for this apparent rejection of Patterson. The only justification advanced for the Court’s decision is that the jury could have used the evidence of self-defense to find that the State failed to carry its burden of proof. Because the jurors were free to consider both Martin’s and the State’s evidence, the argument goes, the verdict of guilt necessarily means that they were convinced that the defendant acted with prior calculation and design, and were unpersuaded that she acted in self-defense. Ante, at 233. The Court thus seems to conclude that as long as the jury is told that the state has the burden of proving all elements of the crime, the overlap between the offense and defense is immaterial.
*240This reasoning is flawed in two respects. First, it simply ignores the problem that arises from inconsistent jury instructions in a criminal case. The Court’s holding implicitly assumes that the jury in fact understands that the ultimate burden remains with the prosecutor at all times, despite a conflicting instruction that places the burden on the accused to disprove the same element. But as pointed out above, the Patterson distinction between defenses that negate an element of the crime and those that do not is based on the legitimate concern that the jury will mistakenly lower the state’s burden. In short, the Court’s rationale fails to explain why the overlap in this case does not create the risk that Patterson suggested was unacceptable.3
Second, the Court significantly, and without explanation, extends the deference granted to state legislatures in this area. Today’s decision could be read to say that virtually all state attempts to shift the burden of proof for affirmative defenses will be upheld, regardless of the relationship between the elements of the defense and the elements of the crime. As I understand it, Patterson allowed burden shifting because evidence of an extreme emotional disturbance did not negate the mens rea of the underlying offense. After today’s decision, however, even if proof of the defense does negate an element of the offense, burden shifting still may be *241permitted because the jury can consider the defendant’s evidence when reaching its verdict.
I agree, of course, that States must have substantial leeway in defining their criminal laws and administering their criminal justice systems. But none of our precedents suggests that courts must give complete deference to a State’s judgment about whether a shift in the burden of proof is consistent with the presumption of innocence. In the past we have emphasized that in some circumstances it may be necessary to look beyond the text of the State’s burden-shifting laws to satisfy ourselves that the requirements of WinsM/p have been satisfied. In Mullaney v. Wilbur, 421 U. S. 684, 698-699 (1975) we explicitly noted the danger of granting the State unchecked discretion to shift the burden as to any element of proof in a criminal case.4 The Court today fails to discuss or even cite Mullaney, despite our unanimous agreement in that case that this danger would justify judicial intervention in some cases. Even Patterson, from which I dissented, recognized that “there are obviously constitutional limits beyond which the States may not go [in labeling elements of a crime as an affirmative defense].”5 432 U. S., at 210. Today, however, the Court simply asserts that Ohio law properly allocates the burdens, without giving any indication of where those limits lie.
Because our precedent establishes that the burden of proof may not be shifted when the elements of the defense and the elements of the offense conflict, and because it seems clear *242that they do so in this case, I would reverse the decision of the Ohio Supreme Court.
II
Although I believe that this case is wrongly decided even under the principles set forth in Patterson, my differences with the Court’s approach are more fundamental. I continue to believe that the better method for deciding when a State may shift the burden of proof is outlined in the Court’s opinion in Mullaney and in my dissenting opinion in Patterson. In Mullaney, we emphasized that the state’s obligation to prove certain facts beyond a reasonable doubt was not necessarily restricted to legislative distinctions between offenses and affirmative defenses. The boundaries of the state’s authority in this respect were elaborated in the Patterson dissent, where I proposed a two-part inquiry:
“The Due Process Clause requires that the prosecutor bear the burden of persuasion beyond a reasonable doubt only if the factor at issue makes a substantial difference in punishment and stigma. The requirement of course applies a fortiori if the factor makes the difference between guilt and innocence. ... It also must be shown that in the Anglo-American legal tradition the factor in question historically has held that level of importance. If either branch of the test is not met, then the legislature retains its traditional authority over matters of proof.” 432 U. S., at 226-227 (footnotes omitted).
Cf. McMillan v. Pennsylvania, 477 U. S. 79, 103 (1986) (Stevens, J., dissenting) (“[I]f 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”).
There are at least two benefits to this approach. First, it ensures that the critical facts necessary to sustain a conviction will be proved by the state. Because the Court would *243be willing to look beyond the text of a state statute, legislatures would have no incentive to redefine essential elements of an offense to make them part of an affirmative defense, thereby shifting the burden of proof in a manner inconsistent with Winship and Mullaney. Second, it would leave the States free in all other respects to recognize new factors that may mitigate the degree of criminality or punishment, without requiring that they also bear the burden of disproving these defenses. See Patterson v. New York, 432 U. S., at 229-230 (Powell, J., dissenting) (“New ameliorative affirmative defenses . . . generally remain undisturbed by the holdings in Winship and Mullaney” (footnote omitted)).
Under this analysis, it plainly is impermissible to require the accused to prove self-defense. If petitioner could have carried her burden, the result would have been decisively different as to both guilt and punishment. There also is no dispute that self-defense historically is one of the primary justifications for otherwise unlawful conduct. See, e. g., Beard v. United States, 158 U. S. 550, 562 (1895). Thus, while I acknowledge that the two-part test may be difficult to apply at times, it is hard to imagine a more clear-cut application than the one presented here.
hH I — I I — I
In its willingness to defer to the State’s legislative definitions of crimes and defenses, the Court apparently has failed to recognize the practical effect of its decision. Martin alleged that she was innocent because she acted in self-defense, a complete justification under Ohio law. See State v. Nolton, 19 Ohio St. 2d 133, 249 N. E. 2d 797 (1969). Because she had the burden of proof on this issue, the jury could have believed that it was just as likely as not that Martin’s conduct was justified, and yet still have voted to convict. In other words, even though the jury may have had a substantial doubt whether Martin committed a crime, she was found guilty under Ohio law. I do not agree that the Court’s au*244thority to review state legislative choices is so limited that it justifies increasing the risk of convicting a person who may not be blameworthy. See Patterson v. New York, supra, at 201-202 (state definition of criminal law must yield when it “ ‘offends some principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental’ ” (quoting Speiser v. Randall, 357 U. S. 513, 523 (1958))). The complexity of the inquiry as to when a State may shift the burden of proof should not lead the Court to fashion simple rules of deference that could lead to such unjust results.
Indeed, this type of instruction has an inherently illogical aspect. It makes no sense to say that the prosecution has the burden of proving an element beyond a reasonable doubt, and that the defense has the burden of proving the contrary by a preponderance of the evidence. If the jury finds that the prosecutor has not met his burden, it of course will have no occasion to consider the affirmative defense. And if the jury finds that each element of the crime has been proved beyond a reasonable doubt, it necessarily has decided that the defendant has not disproved an element of the crime. In either situation the instructions on the affirmative defense are surplusage. Because a reasonable jury will attempt to ascribe some significance to the court’s instructions, the likelihood that it will impermissi-bly shift the burden is increased.
Of course, whether the jury will in fact improperly shift the burden away from the state is uncertain. But it is “settled law . . . that when there exists a reasonable possibility that the jury relied on an unconstitutional understanding of the law in reaching a guilty verdict, that verdict must be set aside.” Francis v. Franklin, 471 U. S. 307, 323, n. 8 (1985).
The accused also must have avoided the danger if possible, and must not have been at fault in creating the threatening situation. See State v. Robbins, 58 Ohio St. 2d 74, 79-80, 388 N. E. 2d 755, 758 (1979).
This risk could have been reduced — although in my view, not eliminated — if the instructions had made it clear that evidence of self-defense can create a reasonable doubt as to guilt, even if that same evidence did not rise to the level necessary to prove an affirmative defense. But the instructions gave little guidance in this respect. The trial court simply told the jury that the prosecution must prove the elements of the crime, and the defendant must prove the existence of the defense. The instructions gave no indication how the jury should evaluate evidence that affected an element of both the crime and the defense. Cf. Francis v. Franklin, supra, at 322 (“Nothing in these specific sentences or in the [jury] charge as a whole makes clear . . . that one of these contradictory instructions carries more weight than the other”).
We noted, for example:
“[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. It would only be necessary to redefine the elements that constitute different crimes, characterizing them as factors that bear solely on the extent of punishment.” 421 U. S., at 698.
See also McMillan v. Pennsylvania, 477 U. S. 79, 86 (1986) (“[I]n certain limited circumstances Winship’s reasonable-doubt requirement applies to facts not formally identified as elements of the offense charged”).