The criminologists surveyed included - 1) Fellows in the American Society of Criminology (ASC), (2) Winners of the ASC’s Sutherland Award, the highest award given by that organization for contributions to criminological theory, or (3) Presidents of the ASC between 1997 and the present. Those presidents before 1997 had been included in the prior survey. Respondents were asked to base their answers on existing empirical research, not their views on capital punishment.
Nearly 78% of those surveyed said that having the death penalty in a state does not lower the murder rate. In addition, 91% of respondents said politicians support the death penalty in order to appear tough on crime – and 75% said that it distracts legislatures on the state and national level from focusing on real solutions to crime problems. Over all, 94% agreed that there was little emperical evidence to support the deterrent effect of the death penalty. And 90% said the death penalty had little effect overall on the committing of murder. Additionally, 91.6% said that increasing the frequency of executions would not add a deterrent effect, and 87.6% said that speeding up executions wouldn't work either.
Public opinion also reflects these findings. In a 2006 Gallup Poll, only 34% of respondents agreed that “the death penalty acts as a deterrent to the commitment of murder, that it lowers the murder rate.” In 2004, 62% of people said the death penalty was not a deterrent. By contrast, in 1985, 62% believed the death penalty acted as a deterrent to murder.(Source: M. Radelet & T. Lacock, "Do Executions Lower Homicide Rates? The Views of Leading Criminologists," 99 Journal of Criminal Law & Crimonology 489, Northwestern University (2009)).
See DPIC's Deterrence page.