The question of whether the death penalty deters murders has set off an intense new debate about one of the central justifications for capital punishment, reports the New York Times. A dozen recent studies assert that executions save lives. For each inmate put to death, the studies say, 3 to 18 murders are prevented. The effect may be most pronounced in Texas and other states that execute condemned inmates relatively often and quickly.
Economists compared the number of executions in different jurisdictions with homicide rates over time – while trying to eliminate the effects of crime rates, conviction rates, and other factors – and say that murder rates tend to fall as executions rise. H. Naci Mocan, an economist at Louisiana State University, opposes the death penalty but “my research shows that there is a deterrent effect.” Legal scholars say the theories of economists do not apply to the violent world of crime and punishment. Critics say they are based on faulty premises, insufficient data, and flawed methodologies. The death penalty “is applied so rarely that the number of homicides it can plausibly have caused or deterred cannot reliably be disentangled from the large year-to-year changes in the homicide rate caused by other factors,” says Yale law Prof. John Donohue III, a law professor at Yale with a doctorate in economics, and Justin Wolfers, an economist at the University of Pennsylvania. “The existing evidence for deterrence is surprisingly fragile.” Law Prof. Cass Sunstein of the University of Chicago said he shifted “from being against the death penalty to thinking that if it has a significant deterrent effect it's probably justified.”