Deterrent Effect of Imprisonment

During the last decades, societies have largely used incarceration as a central crime control tool. Between 1970 and 2008, the prison population per 1,000 inhabitants increased by a factor of more than 4.5 in the USA. Despite a dramatic difference in incarceration levels between the two sides of the Atlantic, also in European countries, prison population increased by a factor between two and three over the period 1970–2008 (Buonanno et al. 2011). This massive increase in incarceration had been coupled with a strong debate in social sciences over the magnitude of its impact on crime rates and over the reasons why crime rates might react to changes in prison population. Those favoring an increase in the severity of the criminal justice system have often argued that increasing prison sentences will lead prospective criminals to reduce their criminal activity. Criminals in fact would weight costs and benefits of crime, and an increase in the cost of criminal activities fol