Prisons and jails serve the dual purposes of punishment and housing for those who have been convicted of crimes, and those who are awaiting trial. The main difference between the two institutions is that prisons exclusively house and punish convicted felons while those housed in jails could be awaiting trial or convicted of a misdemeanor. This important difference leads to a number of similarities, as well as differences in methodology.

Prisons fulfill their purposes through different means, defined by the type of prison. These purposes are tailored to suit the inmates confined in the prison. Minimum security prisons are designed for prisoners who are nonviolent, and require little supervision and control in comparison to other convicted criminals. In these facilities, security may be more lax and the prisoner-to-correctional officer ratio may be low. These prisons often serve a larger facility like a military base in order to provide work opportunities for the inmates. Low security prisons are similar, but often lack the attachment to larger facilities. Medium security prisons often have a higher number of guards per inmate, and serve to provide stronger security for higher-risk inmates. All three of these prisons provide rehabilitative programs for inmates (BOP). Maximum security prisons staff the largest number of correctional officers per inmate, and serve largely to secure and control inmates. The most dangerous inmates will be housed in maximum security facilities, and access to rehabilitative programs is restricted because of security concerns (BOP).

This classification system is one of the main strategies for dealing with inmate violence in the prison system. Because classifications of violent prisoners will necessitate their movement to a higher security facility, inmates may be removed from the population. In addition, prisons implement internal administrative punishments for inmates who violate prison rules. These punishments include the loss of good time, and segregation in secured housing units. Jails may use similar methods to control violence, and some systems operate in different ways in order to deal with a high level of violence from inmates. Jails operating in areas with high rates of violent crime, such as in Chicago, will operate more like a higher security prison, while most jails will seem more closely related to medium or low security prisons.

Though the methods may vary based on the needs of a community or the specific prisoners confined to a facility, the main purposes of prison as an institution are the same. First, prisons protect the public, by separating criminal offenders from the general public. Prisons also rehabilitate and punish offenders, providing a space in which they can be controlled and trained during the period of incarceration. The possibility of a prison sentence subsequently acts as a deterrent for people on the outside who may commit crimes. These purposes intertwine and appropriately form the basis for the creation of a system of punishment and incarceration (Carlson and Simon, 120).

While a jail system is similar and certainly serves the same function, a jail serves also as an administrative holding facility for people suspected of a crime. While awaiting trial and paperwork, a suspect will be housed and, in many cases, punished in the same way as a convicted criminal who resides in the same jail. This is simply to ensure the location of the prisoner and, often, the ability to hold a smooth and incident-free trial (Carlson and Simon, 200).

This system is based on the judicial system, and the public’s judgment of appropriate punishment for crimes. The concept of parole is one that is internal to the system, and allows a parole board to decide if an inmate should be released based on a number of factors. The truth-in-sentencing movement affects this process because the movement seeks to eliminate the ability of a parole board to undermine the will of the judge and the public in the sentencing phase of a trial (Brodeur).