Capital punishment has been applied in North America virtually since the first European settlers arrived. It has been estimated that about 16,000 people have been legally executed in the United States and its colonial predecessors; an unknown additional number of persons have died as a result of extrajudicial executions.

Despite the long history of the death penalty in the United States, modem death penalty jurisprudence can be directly traced to 1972 when the United States Supreme Court decided Furman v. Georgia. One of the longest and most fractured opinions in the Court’s history, Furman held that the death penalty, as it was then applied by the states, violated the cruel and unusual punishments clause of the Eighth Amendment because its imposition was arbitrary and capricious. The controlling opinions held that then-existing death penalty statutes gave juries unfettered discretion to decide when to impose the death penalty for potential capital crimes. Since there was “no meaningful basis for distinguishing the few cases in which it is imposed from the many cases in which it is not,” these opinions held that the death penalty was cruel and unusual “in the same way as being struck by lightning is cruel and unusual,” and that it was therefore unconstitutional.