Criminal rehabilitation refers to attempts to improve
criminals morally or psychologically so that they do not commit more crimes. This rehabilitation may be carried out in prisons or, subsequent to their release, in so-called "halfway houses" or while they mingle with society at large.
Liberals believe that this is an appropriate goal for society to pursue, while
conservatives doubt its effectiveness. 
Rehabilitation is commonly the basis of the criminal justice system
in Denmark and Sweden. Despite pessimism as to its effectiveness, or even a possible causal
connection, Denmark and Sweden have some of the lowest crime rates in the Western World.