Commonwealth v. York

Commonwealth v. York, 50 Mass. (9 Metcalf) 93 (1845), is a precedent-setting American criminal case that established the principle that although the prosecution must prove all elements of a crime beyond a reasonable doubt, the defendant bears the burden of proving the defense of provocation, which pertains to the defendant's mental state.^: 17 This ruling was consistent with Blackstone's Commentaries, which held that prosecution must prove the defendant committed a criminal act, and the defendant must then prove "circumstances of justification, excuse and alleviation".^: 17 However, in federal courts, but not state all courts, this precedent was later modified by Davis v. United States (1895), which established the presumption of innocence regarding a defendant's mental state of being "legally capable of committing crime".^: 17