DPI’s “What to Know” series examines capital punishment from multiple angles, one topic at a time. Each installment provides essential facts and data on specific aspects of the death penalty.
Why it matters: Deterrence is among the most commonly cited justifications for the death penalty, yet decades of research have failed to produce credible evidence that use of the death penalty has an impact on homicide rates.
Key Facts:
- 88% of the nation’s leading criminologists said they did not believe the death penalty deters homicides. Just 9% agreed that “the death penalty significantly reduces the number of homicides.”
- When states have abolished the death penalty, murder rates have not followed any consistent pattern of change. Rates in states that formerly retained the death penalty follow national trends rather than spiking or falling after abolition.
Studies Consistently Debunk Assertions that the Death Penalty Deters Homicide
In 2012, the National Research Council (NRC) released a comprehensive review, Deterrence and the Death Penalty, of more than three decades of post-Gregg v. Georgia (1976) research that concluded existing studies on deterrence “are not informative about whether capital punishment decreases, increases, or has no effect on homicide rates,” and explicitly recommends that they “not be used to inform deliberations” about the death penalty. The NRC identified three compounding flaws in existing deterrence research: studies fail to account for the effects of non-capital punishments; they rely on implausible models of how potential murderers perceive and respond to execution risk; and they are built on statistical assumptions that are not credible and cannot be confirmed.
“…[C]laims that research demonstrates that capital punishment decreases or increases the homicide rate by a specified amount or has not effect on the homicide rate should not influence policy judgments about capital punishment.”
Unlike like its 1978 predecessor report, the NRC’s 2012 report offered three concrete recommendations for future research: collect stronger data on capital and non-capital components of the punishment scheme for homicides; study how potential murderers actually perceive and respond to the risk of sanction, rather than assuming response to objective statistics; and use statistical methods that rely on “less strong and more credible assumptions.”
“The scientific community has found no reliable evidence of the death penalty being a deterrent to homicides…Murder rates are and have been independent of the imposition of the death penalty of the institution of having a death penalty.”
Other Countries Experience Lower Murder Rates Than the U.S. — Without the Death Penalty
- In the European Union, where all member countries have abolished the death penalty, every country has a lower murder rate than the United States.
- More broadly, as of 2018, of the eleven countries that had abolished the death penalty between 2008 and 2018, ten experienced a decline in murder rates post-abolition.
