DOES the threat of the death penalty discourage potential murderers? Dozens of studies over the past three decades have searched for an answer: yet all of them are flawed.
At least, so concludes a damning report published this week by the US , which looked at all of the studies published since the US lifted a four-year ban on the death penalty in 1976. 鈥淭he unfortunate conclusion is that we can鈥檛 learn anything from these studies,鈥� says of Northwestern University in Evanston, Illinois, a member of the report committee.
The report found that none of the studies factored in the deterrent effect of other punishments, such as life imprisonment. Secondly, many researchers made unwarranted assumptions that potential murderers would be aware of, and act on, trends in the number of executions. Finally, many studies reached unjustified conclusions about whether individual executions subsequently altered homicide rates.
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Manski says that the report examined research exclusively on the deterrent effect of the death penalty, not whether society accepts or rejects it. The current trend is for US states to repeal the death penalty.
What might be more valuable in future, he says, is research on what deters people from all sorts of crime, and inclusion of data on the effects of other deterrents.