| There has been a need to distinguish between the practice of punishment and the institution of punishment. Everyone has accepted that there is a distinction, but no one has appreciated or understand it. John Rawls, in Punishment, attempts to discern this distinction and explain it's importance while defending utilitarianism.
There are two justifications for punishment. The first being that if one does wrong, one should suffer proportionally. This is generally an accepted view; criminals should be punished. This is referred to as the retributive view. A retributive viewpoint on punishment is one that looks back. The judge and jury look back onto what a criminal has done in order to ascertain his guilt and subsequent punishment. This is a case by case stand. The judge looks at each individual criminal and decides what shall be his fate.
The other view is a utilitarian view. Punishing those who do wrong will set an example to the rest of society, and they will, in turn, do nothing wrong. Thus, punishing criminals would benefit society in the long run. This view is forward looking. A legislator will look at a problem, such as a way to stop crime, and will create laws. These laws will create an institution, such as punishment or criminals. In the long run, this institution will. The utilitarian view then looks ahead to the consequences as a way to justify punishing wrongdoers. Therefore, the legislator creates a practice, with total disregard to each individual case.
This being the case, the question arises as to whether an innocent man will be convicted. The retributive view says no. Since an innocent man is innocent, according to his case, he is free. The innocent man has done no wrong, and as such, will not and cannot be further prosecuted. The utilitarian view, on the other hand, will allow for the punishment of an innocent man. If the innocent man being prosecuted will, in some way, benefit the society by scaring real criminals, then this act is morally justified, however misguided.
It appears that utilitarianism justifies too much. Since they follow utilitarian rules instead of the retribution view of justice, anything that benefits society is morally right. However, in order to understand the justification for an institution, one much understand the authority from which the institution derives its power. If a crooked authority were in charge of an institution, a utilitarian justification would be non-existent. In order for an institution to be justified, not only does the idea behind the institution need to be moral in the right, but the authority pushing that institution has to be morally right. | 
