Mullaney v. Wilbur

The State of Maine requires a defendant charged with murder to prove that he acted “in the heat of passion on sudden provocation” in order to reduce the homicide to *685manslaughter. We must decide whether this rule comports with the due process requirement, as defined in In re Winship, 397 U. S. 358, 364 (1970), that the prosecution prove beyond a reasonable doubt every fact necessary to constitute the crime charged.

I

In June 1966 a jury found respondent Stillman E. Wilbur, Jr., guilty of murder. The case against him rested on his own pretrial statement and on circumstantial evidence showing that…