Gary Duncan, a Black teenager in Louisiana, was denied a jury trial on a simple-battery charge because the maximum sentence was two years. The Court held the Sixth Amendment's jury-trial guarantee is 'fundamental to the American scheme of justice' and therefore applies to the states. Justice White's opinion drew the still-controlling line: any offense carrying more than six months' possible imprisonment is 'serious' enough to trigger the jury-trial right. Duncan is a landmark of selective incorporation and a foundational protection against arbitrary state prosecution.