Most societies at some time or other have endorsed the use of the death penalty. Ancient Roman and Judaic cultures practiced retributive justice, adhering to the rule of "an eye for an eye." The United States inherited its use of capital punishment from European settlers in the seventeenth century, promoting the notion that heinous crimes deserved severe punishment. In the eighteenth century, however, philosophers began to question the ethics of the death penalty. Italian criminologist Cesare Beccaria condemned capital punishment as an ineffective and grossly inhumane deterrent to crime. Conversely, German philosopher Immanuel Kant claimed that execution was the fairest punishment for murder, arguing that even guilt-ridden killers should die in order to gain release from their anguish. Such arguments concerning the ethics of capital punishment continue to spark controversy to the present day.

Contemporary supporters of capital punishment maintain that execution is...