Based on liberal principles, we argued before that individuals should not have the right to voluntarily terminate their lives. We shall consider now whether the State should have the right to capital punishment.
Most countries have renounced that right, but about 60% of humankind still lives under regimes with death penalty. Some of those regimes are dictatorships, like China, Iran or Saudi Arabia, but others are democracies, such as Taiwan, Japan and the United States.
Leaving aside the case of dictatorships and countries at war where human rights are ignored, we shall focus on the use of death penalty to punish non-political crimes in democratic countries such as the United States.
The case for using the death penalty to punish horrible crimes (e.g. homicide) is usually based on the principles of reciprocity, proportionality and deterrence. All these arguments are flawed.
The principle of reciprocity has its roots in the Hammurabi Code that introduced the law of an eye for an eye. However, it is now clear that you cannot correct a wrong by repeating it. Moreover, vengeance is not certainly among the enlightened virtues.
The principle of imposing penalties proportional to the seriousness of the offense is obviously just, but must be kept with reasonable boundaries. For instance, the assumption that death is the ultimate punishment is false. Torture, forced labor or isolation can be used as the harshest forms of punishment. However, societies need to balance redemption and punishment on the basis of its costs and benefits to society as whole; as well as the risk of committing irreparable mistakes in the administration of justice.
It is certainly true that lenient punishments or unrealistic beliefs in the recuperation of criminals can encourage crime. This can be easily observed in countries like Portugal which, after introducing a maximum effective prison sentence of 15 years and various forms of soft prison regimes and house arrests, experienced one of the highest rises in crime in the world.
Nevertheless, the statistics for the United States, where not all states have death penalty, also show that capital punishment does not work as a deterrent of violent crime. First, some homicides are not premeditated (e.g. passion crimes). Second, crimes are mostly the result of widespread possession of lethal weapons that often turn what would be simple fights into murders. Finally, and not least important, the perpetrators of premeditated crimes believe that the odds of being caught and executed are small and worth taking.
To sum up, none of the three arguments in favor of death penalty is strong enough to waive the liberal principle about the inviolability of the right to life. Only fallacious reasoning or prejudice can justify this barbarous historical relic.