“An efficient legal system should focus on reintegration and reconciliation, instead of on penance and redress.”
Recently, in the Netherlands, the role of revenge in the legal system was covered in the news, as our Minister of Justice stated that being killed is a risk of being a thief  and some people argued that with this, he was actually dignifying revenge . Subsequently, the word ‘inbrekersrisico’ (risk of being a burglar) was chosen in the top-3 of new words in the Dutch language. This got me thinking on the idea of revenge and redress, why is it so deeply rooted in our society that an eye goes for an eye?
I assert that society as a whole would be better of if we would focus more on getting criminals to function in society and less on getting justice for victims. More concrete: we should not punish people by putting them in jail, it might feel fair to victims, but that should not be the core principle of a justice system. We should inhibit some form of separation of concerns. I believe this is also a good principle for legal systems. When a crime has been committed, two things need to happen: the victim needs help/support/compensation and the perpetrator must be prevented to not commit more crimes. Combining those two concerns leads to problems, as victims, not being legal experts, might not be the best judges of what is best for a victim and hence for society. So these two things should be separated, as opposed to more tightly coupled, as politicians have argued for recently.
(Note: I do think jail time is okay for people who we want to permanently remove from society, like serial killers). So, what do experts say?
There are different, conflicting criminological theories on the effects of detention on recidivism.
- Deterrence theory A theory is favor of detention is deterrence theory, that assumes that people will refrain from criminal activities out of fear for future punishment. The tougher the sentence, the bigger the deterring effect, so from this perspective jail time would be more effective than alternative sentences like community service or mandatory training.
- Differential association developed by Sutherland  takes a different stand and asserts that all behavior is learned by interaction and communication and that prisons as such, can act as school for criminals.
- Social control theory states that social control from parents, friends and colleagues who disapprove criminal behavior will help to prevent perpetrators from criminal acts. It is believed that by being in jail, these connections diminish or disappear. Community service is aimed at keeping or even intensifying those connections.
- Finally, Labeling theory argues that the negative stigma (label) associated with detention can increase social isolation and changes of a criminal life style. 
Note: A more detailed overview of above theories can be found in 
Although most theories are not in favor of jail sentences, there no final answer and we are in need of some empirical data. Form a research perspective, it would be best to perform a randomized trail, in which defendants with a similar background and crime are randomly sentenced either detention or community service. However, there are ethical reason not to perform such experiments. There has been one such study, but its results on the long term are debated by other papers .
Therefore in the Netherlands, a matching study was conducted, based on characteristics of the crime and the criminal, two situations are matched, one in which the sentence was detention less than 6 months and another in which community service was given. They chose jail time less than 6 months because in the Netherlands community service is only viewed as an alternative to sentenced of up to 6 months.
In all studies cases, the sentence was for the first crime ever committed. There were able to match 4.246 sentences (so 2123 times detention coupled with 2123 times community service) Their results show that those sentenced to community service recommit a crime 47% fewer than those sentenced to jail time. These results hold for different types of crimes, including violent crimes.
Costs of detention
In the Netherlands the costs for six month of detention are €34.200. 240 hours of community service cost only €4.200.
Focusing on rehabilitation, rather than tough sentencing is more efficient than a focus on punishment: it will lower both costs of executing the sentences and the total crimes in the future.
Note: It was really interesting to read research papers from another discipline, should have done that earlier. It showed me, that although doing a PhD is a very specialized effort, it still also prepares you to be researcher in a very broad way. This is why I love the Dutch proposition system.
 http://nos.nl/artikel/422798-teeven-dood-is-inbrekersrisico.html (Dutch)
 R. Paternoster, Capital punishment in America (1991)
 E. Sutherland, Principles or criminology (1947)
 G. Bazemore & D. Maloney, Rehabilitating community service: Toward restorative service sanctions in a balanced justice system (1994)
 M. Killias, M. Aebi & D. Ribeaud, Does community service rehabilitate better than short-term imprisonment Results of a controlled experiment. (2000)
 G. Gilliéron, C. Poglia F. Villard J. Vuille C. Perisset & M. Killias, Bessere Resozialisierung nach gemeinnütziger Arbeit? Ein vergleich mit kurzen Freiheitsstrafen (2006)
 H. Wermink, A. Blokland, P. Nieuwberta & N. Tollenaar, Recidive na werkstraffen en gevangenisstraffen: een gemachte vergelijking.
 G. Becker. Outsiders: Studies in the sociology of deviance (1963)