Mullaney v. Wilbur

Supreme Court of the United States · 1975 · Criminal Law

421 U.S. 684 (1975)

Updated August 1, 2026

Criminal Lawburden of proofdue processreasonable doubtheat of passionsudden provocationmanslaughtermurder

Facts

Maine treated intentional or criminally reckless unlawful killings as felonious homicide, punishable as murder unless the defendant proved by a preponderance of the evidence that he acted in the heat of passion on sudden provocation, in which case the offense was punished as manslaughter. At respondent's trial for fatally assaulting Claude Hebert, the prosecution introduced respondent's statement that he attacked Hebert in a frenzy provoked by a homosexual advance. The defense offered no evidence but argued alternatively that the killing lacked criminal intent or, at most, was manslaughter because it occurred in the heat of passion on sudden provocation. The jury was instructed that malice aforethought would be conclusively implied from an intentional and unlawful homicide unless respondent proved heat of passion on sudden provocation, and it convicted him of murder.

Issue

Whether Maine may, consistent with the Due Process Clause, require a homicide defendant to prove by a preponderance of the evidence that he acted in the heat of passion on sudden provocation in order to reduce murder to manslaughter. More specifically, the question was whether Winship's requirement that the prosecution prove beyond a reasonable doubt every fact necessary to constitute the crime charged applies to this mitigating fact that determines the degree of criminal culpability and punishment.

Rule

The Due Process Clause requires the prosecution to prove beyond a reasonable doubt the absence of heat of passion on sudden provocation when that issue is properly presented in a homicide case. A State may not avoid Winship by formally defining such a fact as relevant only to punishment rather than as an element of a separately labeled crime; due process looks to the substance, operation, and effect of the law.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In Oregon, a homicide statute defines all unjustified intentional killings as a single offense called criminal homicide. The statute provides that the defendant may reduce the punishment from mandatory life imprisonment to a maximum of 15 years only by proving, by a preponderance of the evidence, that he acted in the heat of passion after sudden provocation, and Noah Benton introduces evidence supporting that claim at trial in Portland.

If Noah challenges the burden allocation on due process grounds, how should a court rule?

Explanation. Due process looks to the substance and effect of the law, not the State's labels. When the issue of heat of passion on sudden provocation is properly presented in a homicide case, the prosecution must prove its absence beyond a reasonable doubt. A State may not require the defendant to bear the ultimate burden of persuasion on that issue merely by characterizing it as punishment-related.