Capital punishment functions as an ultimate deterrent against homicide to the extent that a convicted offender who has been executed cannot repeat his or her crime. Whether or not the existence of a death penalty statute actually reduces the incidence of homicide in society by causing some murders not to happen necessarily remains difficult to establish.
An ultimate deterrent
Some critics of the criminal justice system point out that capital punishment potentially functions as a deterrent against homicide, since the severe penalty of execution prevents convicted individuals from re-offending in the future. For example, in the United States, criminologists have documented cases in which some murderers engage in serial crime sprees, ruthlessly taking the lives of a series of innocent individuals, sometimes in a calculated manner.
For example, the notorious Ted Bundy (1946-1989) several decades ago cruelly murdered a series of people. Although his pattern varied sometimes, he often intentionally sought out people to harm. Although the exact number of his victims may never be determined, before his death he reportedly confessed to perpetrating well over twenty homicides.
A supporter of capital punishment might reasonably argue that if Ted Bundy had been apprehended, tried, convicted and then executed following the demise of his first known victim, many other lives might well have been spared. He escaped from custody at one point and resumed his killing rampage before finally being apprehended and brought to trial.
Does a death penalty deter potential homicides?
Arguably, the existence of capital punishment as a legal sanction alone might not deter all individuals from committing all homicides. However, the presence of a severe penalty likely causes some offenders to spare the lives of some potential victims under some circumstances.
For example, many jurisdictions in the United States specifically impose a death sentence upon homicides directed against particular categories of at-risk people, such as law enforcement officers, or victims murdered during the course of a serious felony, (such as an armed robbery or an arson). It seems likely that the rationale underlying these types of legal provisions involves seeking to safeguarding the public through the deterrence of some particularly egregious crimes.
Police officers may encounter dangerous offenders during the course of performing routine job-related functions, for instance. And both felony-homicide provisions involve situations in which potentially lethal harm could easily befall the victims of crime.
So an additional basis for imposing the death penalty in the case of homicide directed against law enforcement officers involves the importance of reinforcing their authority in certain high risk situations. A criminal encountering a law enforcement officer during the course of committing a crime might not be as likely to harm the officer if the offender appreciated that doing so would incur a capital murder charge.
In some cases, draconian penalties might not matter to some criminals; but if even a small percentage of offenders do indeed refrain from committing lethal violence against some victims on account of capital punishment provisions in the law, then to some extent death penalty legislation could be deemed to wield a deterrent effect against potential crime.