There are several reasons to punish a person for a crime. A person may want to rehabilitate a Defendant or let them have what’s coming to them. Here are some reasons,
Punishment based on Utilitarianism (Deterrence)
The utilitarian theory is essentially one of deterrence – punishment is justifiable if, but only if, it is expected to result in a reduction of crime. Punishment must be proportional to the crime. This means that that punishment to be inflicted in the amount required, but no more than is required, to satisfy utilitarian crime prevention goals.
Utilitarians consider the effect of a form of punishment in terms of both general deterrence and specific (or individual) deterrence. When the goal is general deterrence, punishment is imposed in order to dissuade the community at large to forego criminal conduct in the future. When the goal is specific deterrence, punishment is meant to deter future misconduct by an individual defendant by both preventing him from committing crimes against society during the period of his incarceration (incapacitation), and reinforcing to him the consequences of future crimes (intimidation).
Punishment based on Rehabilitation – Another form of utilitarianism is rehabilitation (or reform). Examples of rehabilitative “punishment” include: psychiatric care, therapy for drug addiction, or academic or vocational training.
Punishment based on Retributivism – Under a retributive theory of penal law, a convicted defendant is punished simply because he deserves it. There is no exterior motive such as deterring others from crime or protecting society. The goal is to make the defendant suffer in order to pay for his crime. Retributive theory assigns punishment on a proportional basis so that crimes that cause greater harm or are committed with a higher degree of culpability receive more severe punishment than lesser criminal activity.
Punishment based on Denunciation – The denunciation theory holds that punishment is justified as a means of expressing society’s condemnation of a crime. This has both utilitarian and retributive components. Under a utilitarian theory, denunciation is desirable because it educates individuals that the community considers specific conduct improper, It channels community anger away from personal vengeance, and serves to maintain social cohesion. Under a retributive theory, denunciation serves to punish the defendant by stigmatizing him. A sex offender registry is one example of this.