NCPA - National Center for Policy Analysis


June 12, 2007

A series of academic studies over the last half-dozen years claim to settle a once hotly debated argument: whether the death penalty acts as a deterrent to murder. The analyses say yes. They count between three and 18 lives that would be saved by the execution of each convicted killer.

To explore the question, they look at executions and homicides, by year and by state or county, trying to tease out the impact of the death penalty on homicides by accounting for other factors, such as unemployment data and per capita income, the probabilities of arrest and conviction, and more.

Among the conclusions:

  • Each execution deters an average of 18 murders, according to a 2003 nationwide study by professors at Emory University (other studies have estimated the deterred murders per execution at three, five and 14).
  • The Illinois moratorium on executions in 2000 -- imposed by then-Gov. George Ryan and continued by current Gov. Rod Blagojevich -- led to 150 additional homicides over four years following, according to a 2006 study by professors at the University of Houston.
  • Speeding up executions would strengthen the deterrent effect; for every 2.75 years cut from time spent on death row, one murder would be prevented, according to a 2004 study by an Emory University professor.
  • In 2005, there were 16,692 cases of murder and nonnegligent manslaughter nationally; there were 60 executions.

So far, the studies have had little impact on public policy and critics have been vociferous. However, several authors of the pro-deterrent reports said they welcome criticism in the interests of science. They say their work is being attacked by opponents of capital punishment for their findings, not their flaws.

Source: Robert Tanner, "Studies Say Death Penalty Deters Crime," Associated Press/Chattanooga Times Free Press, June 11, 2007.


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