The idea that the
death penalty is a deterent for serious crimes.
Amnesty International cite the following paper:
"Scientific studies have consistently failed to find convincing evidence that the death penalty deters crime more effectively than other punishments. The most recent survey of research findings on the relation between the death penalty and homicide rates, conducted for the United Nations in 1988 and updated in 1996, concluded: "Research has failed to provide scientific proof that executions have a greater deterrent effect than life imprisonment and such proof is unlikely to be forthcoming. The evidence as a whole still gives no positive support to the deterrent hypothesis..."
"Reviewing the evidence on the relation between changes in the use of the death penalty and crime rates, a study conducted for the United Nations in 1988 and updated in 1996 stated that "the fact that all the evidence continues to point in the same direction is persuasive a priori evidence that countries need not fear sudden and serious changes in the curve of crime if they reduce their reliance upon the death penalty".
"Recent crime figures from abolitionist countries fail to show that abolition has harmful effects. In Canada, the homicide rate per 100,000 population fell from a peak of 3.09 in 1975, the year before the abolition of the death penalty for murder, to 2.41 in 1980, and since then it has declined further. In 1998, 22 years after abolition, the homicide rate was 1.83 per 100,000 population, 40 per cent lower than in 1975. The total number of homicides reported in the country fell in 1998 for the second straight year."
- Roger Hood, The Death Penalty: A World-wide Perspective, Oxford, Clarendon Press, revised edition, 1996