The way in which prisoners are treated has become a source of much debate over the last few decades. Whether or not prisoners should be rehabilitated or punished is something that has divided law makers and politicians for more than a century, with both sides offering statistics to support their arguments.
Defenders of prison as a penal system argue that harsh prison sentences and punishing regimes inside gaols act as a deterrent against crime. When faced with the prospect of a longer sentence for a particular crime, such people argue that potential offenders will be less likely to commit a crime, knowing that the consequences will be severe. They often claim that the construction of more prisons contributes to a decline in crime rates and that simple keeping prisoners off the streets is the best solution.
Opponents of this view, however, argue that unless prisoners are reformed in gaol, they are more likely to re-offend upon release. Proponents of reforming the prison system claim that crime rates are more likely to be reduced if prisoners are subjected to rehabilitation programs and enabled to develop skills which will help them adapt back into society upon release. They argue that subjecting prisoners to long, arduous sentences does nothing to deter them from re-offending after release, but indeed only increases the chances of this happening.
I would conclude that education and rehabilitation are the best approaches to dealing with prisoners. Long sentences do little to make people see the error of their ways and there is little evidence to suggest that such measures are effective.