Does the Death Penalty Really Deter Crime?

For the first time in United States history, more Americans believe the death penalty is applied unfairly than fairly – 50% versus 47%, according to a recent Gallup poll conducted on October 2, 2023.  While 53% of Americans currently favor the overall use of the death penalty, this is a dramatic drop from the 60% in 2017, as well as the lowest favorability rating since March 1972 (50%). There are several popular explanations for this decrease in support, such as the additional public expense required to hold executions over a life sentence, and the injustices that occur when courts falsely convict and needlessly sentence innocent people to capital punishment. However, this article will not focus on arguments against the death penalty, but rather on the validity of one of its most popular supporting arguments: deterrence, the concept that people will avoid committing violent crime due to the fear of being put to death.

For the first time in United States history, more Americans believe the death penalty is applied unfairly than fairly.

According to a 2021 Pew Research study, 50% of death penalty supporters currently use the deterrence argument, a statistic that appears quite low considering how often the term deterrence is tossed into the capital punishment debate. Does capital punishment actually work? That question is impossible to answer, as people who seriously considered murder probably would not admit to it and those who do commit murder evidently do not fear or consider capital punishment. 

One method to analyze the validity of deterrence is in comparing murder rates in the 27 death penalty states to the 23 non-death penalty states. In 2019, the FBI’s Uniform Crime Reports gathered the average annual murder rate in the death penalty states and compared it to that of the non-death penalty states. Over the 29-year period, the murder rate in death penalty states was higher than in non-death penalty states. The average percent difference over that period was almost 30%. This evidence is compounded by a November 2023 USA Facts review article stating that the five states with the highest homicide rates — Mississippi (23.7%), Louisiana (21.3%), Alabama (15.9%), New Mexico (15.3%), and South Carolina (13.4%) – all utilize the death penalty, except for New Mexico. 

The New York City Police Department recorded the number of murders in the city over 2000-2022, during which the State of New York abolished the death penalty in 2007. The average number of murders from 2000-2006 was 602, compared to 413 from 2007-2022.While it is true that there is a larger span of years for the latter number (16 years counted versus 7 years counted) making the comparison unbalanced, let us analyze another series of the FBI’s Uniform Crime Reports that counted the murder rates in each year from 1960-2019 in New York City. The thirteen-year range data interestingly demonstrates the opposite effect. From 1994-2006, the average murder rate was 5.9% and from 2007-2019 it was 3.5%. Thus, New York City murder rates have decreased since the abolition of the death penalty.

From this data, it seems almost definite that deterrence through fear of capital punishment is a myth. If deterrence worked, then why would there be higher average murder rates in death penalty states than in non-death penalty states? Why would New York City, the most populated city in the nation, show an overall decline in murder rates in the years following the state’s capital punishment abolition? The data even suggests that the death penalty unintentionally encourages murder given the correlation between lower murder rates and non-death penalty states. Could abolition of the death penalty across all 50 states actually decrease homicide nationwide? Seems likely.

It seems almost definite that deterrence through fear of capital punishment is a myth.

Yet how can we be certain that there were no significant outside variables contributing to all this data? Were there other deterrent methods which were more successful than capital punishment over these periods? Did the surge of public surveillance and expansion in policing after 9/11 prevent murders? What about radical changes in political leadership, or even new home security technologies such as Ring?

Point being, it is immensely challenging to definitively and objectively declare the death penalty as a failed measure of deterrence, and nearly impossible to declare that the death penalty causes higher murder rates. I feel these hypotheses, particularly the former, are quite likely, but there simply is no method of completely eliminating outside variables to objectively establish those two claims. However, it is abundantly clear that deterrence is an unstable – at best – defense for the death penalty, and one that proponents should no longer rely on.

Eric Zimmerman ‘27 studies in the College of Arts & Sciences. He can be reached at e.j.zimmerman@wustl.edu