The death penalty imposed by the state for the punishment of grave crimes. It is certain from Scripture that civil authorities may lawfully put malefactors to death. Capital punishment was enacted for certain grievous crimes in the Old Law, e.g., blasphemy, sorcery, adultery, and murder. Christian dispensation made no essential change in this respect, as St. Paul expressly says: "The state is there to serve God for your benefit. If you break the law, however, you may well have fear: the bearing of the sword has its significance" (Romans 13:4). Among the errors of the Waldenses condemned by the Church in the early thirteenth century was the proposition that denied the lawfulness of capital punishment (Argentré, Collectio de Novis Erroribus,I, 86). St. Thomas Aquinas (1225-74) defends capital punishment of the grounds of the common good. The state, he reasons is like a body composed of many members, and as a surgeon may cut off one corrupt limb to save the others, so the civil authority may lawfully put a criminal to death and thus provide for the common good.
Theologians further reason that, in receiving its authority from God through the natural law, the state also receives from him the right to use the necessary means for attaining its end. The death penalty is such a means. If even with capital punishment crime abounds, no lesser penalty will suffice.
The practical question remains of how effective a deterrent capital punishment is in some modern states, when rarely used or only after long delays. In principle, however, it is morally licit because in the most serious crimes the claims of retribution and deterrence are so demanding that the corrective value of punishment must, if necessary, be sacrificed.