Overview

Deterrence is probably the most commonly expressed rationale for the death penalty. The essence of the theory is that the threat of being executed in the future will be sufficient to cause a significant number of people to refrain from committing a heinous crime they had otherwise planned. Deterrence is not principally concerned with the prevention of further killing by an already convicted death-penalty defendant. That falls under the topic of incapacitation.

Deterrence should not be considered in a vacuum. The critical question is not whether potential criminals will be dissuaded from killing because they would face the death penalty rather than no punishment at all. Other punishments such as life without parole might provide equal deterrence at far less costs and without the attendant risk of executing an innocent person. Whether the death penalty is a proven method of lowering the murder rate has been subjected to many studies over many decades.

It is not enough to compare jurisdictions with the death penalty to those without unless the study controls for the many other variables that could affect the murder rate. For example, lower unemployment rates correlate with lower crime rates. More police involvement in the local community seems to reduce crime. The death penalty affects only a tiny percentage of even those who commit murder. Its effect is very difficult to pinpoint, and the National Academy of Sciences has concluded that past studies have neither proven nor disproven a deterrent effect.

At Issue

If the death penalty is not a proven deterrent to murder, is it worth the excessive costs, risks of error, uncertainty of completion, and other problems that are inherent to its practice? On the political level, the deterrent value of the death penalty is often taken for granted without a careful examination of the research or a consideration of less risky alternatives. This is especially relevant given that death penalty use has been declining dramatically. Most states are not carrying out any executions in a given year.

What DPIC Offers

DPIC has collected many of the deterrent studies that have been conducted in the modern era and has summarized their results. It also provides some of the raw data on which such studies rely, such as the murder rate for each state in each year in the modern era, along with the number of executions and death sentences for each state in the same periods.