The Burden of Proof and the Insanity Defense After Mullaney v. Wilbur

In 1970, the Supreme Court of the United States in the case of In re Winship specified an evidentiary standard of proof for criminal prosecutions as a requirement of the due process clause of the 14th amendment: "Lest there remain any doubt about the constitutional stature of the reasonable doubt-standard, we explicitly hold that the Due Process Clause protects the accused against conviction except upon proof beyond a reasonable doubt of every fact necessary to constitute the crime with which he is charged." Five years later, in Mullaney v. Wilbur, the Court extended Winship to invalidate Maine's statutory scheme of felonious homicide which required the defendant to establish by a preponderance of evidence the mitigating factor of heat of passion on sudden provocation. Under Maine law, malice or the absence of heat of passion was not an element of the crime of felonious homicide. The Supreme Court, nevertheless, required Maine to prove beyond a reasonable doubt the absence of heat of passion because it was a fact "critical to criminal culpability" that affected the severity of the punishment imposed. Maine's new criminal code represents a legislative effort to comply with the mandate of Winship, for it declares that "no person may be convicted of a crime unless each element of the crime is proved beyond a reasonable doubt." Nevertheless, Maine, like most states, continues to designate certain issues as "affirmative defenses" which the defendant must prove by a preponderance of the evidence in order to prevail. This Comment examines the affirmative defense of insanity in light of Winship and Wilbur. Specifically, the thesis of this Comment is that Wilbur expanded the scope of the Winship holding. The reasonable doubt standard is no longer limited to the elements of a crime as formally defined by state law. After Wilbur, any affirmative defense which imposes a persuasion burden upon the defendant is constitutionally suspect. As the First Circuit recently acknowledged, there is "substantial doubt" whether the Constitution permits a state to impose upon a criminal defendant the burden of proving insanity.