Deterrence: Death penalty proponents argue that the execution of convicted murderers deters others from committing murder for fear that they will also be executed, and also that murderers will be incapacitated: once dead, they will have no opportunity to commit additional murders. Death penalty opponents dispute the deterrent effect of capital punishment, arguing that few murderers rationally weigh the possibility that they might face the death penalty before committing a murder. The majority of murders are committed in the heat of passion and/or under the influence of alcohol or drugs, when there is little thought given to the possible consequence of the act. Finally, death penalty opponents do not dispute that execution incapacitates executed murders, but argue that life imprisonment without possibility of parole is equally incapacitating.
II. Retribution: Death penalty proponents justify capital punishment under the principle of retribution -"an eye for an eye" - the belief that punishment should fit the crime. However we do not punish rape with rape, or burn down the house of an arsonist. Therefore we should not punish the murderer with death. Death penalty opponents emphasize the sacredness of life, arguing that killing is always wrong whether by individual or by the state.
III. Judicial error: Death penalty proponents argue that there are sufficient safeguards against executing persons and that the danger of executing the innocent is small. Death penalty opponents argue that there is a danger of executing innocent persons, and cite actual cases in which defendants were erroneously convicted of, and sometimes executed for, capital crimes. They view recent laws, which restrict the appeals process as equal to increasing the potential for executing innocent people. A great example of judicial errors is a study published in 1982 in the Stanford Law Review, which documents 350 capital convictions in which it was later proved that the convict had not committed the crime. Of those, 23 convicts were executed and others spent decades of their lives in prison.
IV. Cost: Death penalty proponents argue that the death penalty is a cost-effective alternative to life imprisonment. Death penalty opponents argue that capital punishment is expensive, costing more than it would cost to imprison murderers for life. Factors Determining Whether A Defendant Dies

Whether or not a death sentence is handed down are not the facts of the crime, but the quality of the legal representation. The overwhelming majority of death row inmates receive substandard legal representation at trial. Almost all capital-crime defendants are indigent when arrested, and are generally represented by court-appointed lawyers, who are inexperienced and underpaid.