This brief instructional bulletin from the National Institute of Justice lists five key pieces of information that can help those who make policies and laws that are based on science. The content is drawn from Daniel S. Nagin's 2013 essay, "Deterrence in the Twenty-First Century," in Crime and Justice in America: 1975-2025.
First, research shows clearly: If criminals think there's only a slim chance they will be caught, the severity of punishment even draconian punishment is an ineffective deterrent to crime. Second, prisons are good for punishing criminals and keeping them off the street, but prison sentences are unlikely to deter future crime. Third, the police deter crime when they do things that strengthen a criminal's perception of the certainty of being caught. Fourth, laws and policies designed to deter crime are ineffective partly because criminals know little about the sanctions for specific crimes. Fifth, according to the National Academy of Sciences, "Research on the deterrent effect of capital punishment is uninformative about whether capital punishment increases, decreases, or has no effect on homicide rates."