Opponents of the death penalty argue that it violates the prohibition against “cruel and unusual punishments" in the Ei^xth Amendment to the Constitution. They claim that the death penalty is not an effective means of deterring crime, is unnecessarily barbaric in nature，cheapens human life and puts a government on the same base moral level as chose criminals involved in murder. They also argue that the death penalty is applied unequally. A large proportion of those executed have been poor, uneducated, and nonwhite. In contrast, advocates of the death penalty argue that it deters crime, improves the community by making sure that convicted criminals do not offend again, provides closure to surviving victims or loved ones, and is a just penally for their crime. They chaim that a mere jail sentence for a multiple murderer or rapist-murderer seems unjust compared with the damage inflicted on sodcty and the victims. In many cases, a life sentence means less than ten years in prison under the current early-release and parole policies in many states. Convicted murderers have been set free, and some have killed again.

Capital punishment in the United States varies by jurisdiction. Some jurisdictions have banned it, others have suspended its use，but others are trying to expand its applicability. Prior to 1971, the death penalty was ofBcially sanctioned by about half of the states. Federal law also retained the death penalty. However, no one had actually suffered the death penalty since 1967 because of numerous direct challenges to the constitutionality of capital punishment.

In 1972，the Supreme Court ruled that capital punishment violated the Eighth and Fourteenth Amendment prohibitions against cruel and unusual punishment and due process of law. Nevertheless, the justices left open the possibility that capital punishment would be constitutional if it was specified for certain kinds of crime and applied uniformly.

After this decision, a majority of states rewrote their death penalty laws to try to ensure fairness and uniformity of application. Generally，these laws mandate the death penalty for murders committed during rape, robbery, hijacking, or kidnapping; murder of prison guards; murder with torture; and multiple murders. They call for two trials to be held — one to determine guilty or innocence and another to determine the penalty. At the second trial, evidence of “aggravating” and “mitigating” factors must be presented; if there are aggravating factors but not mitigating factors, the death penalty is mandatory.

The revised death penalty laws were upheld in a series of cases that came before the Supreme Court in 1976. The Court concluded that “the punishment of death does not invariably violate the Constitution' and “a large proportion of American society continues to regard it as an appropriate and necessary criminal sanction”. Moreover, the Court held that the social purposes of retribution and deterrence justify the use of death penalty. But, capital punishment is plied rarely today. There were 37 executions in 2008. That is the lowest number since 1994.

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