Prisons in the United States are operated by both the federal and state governments as incarceration is a concurrent power under the Constitution of the United States. Imprisonment is one of the main forms of punishment for the commission of felony offenses in the United States. Less serious offenders, including those convicted of misdemeanor offenses, may be sentenced to a short term in a local jail or with alternative forms of sanctions such as community corrections (halfway house), probation, and/or restitution. In the United States, prisons are operated at various levels of security, ranging from minimum-security prisons that mainly house non-violent offenders to Supermax facilities that house well-known criminals and terrorists.
The United States has among the highest incarceration rates in the world. More people are behind bars in the United States than any other country. As of 2006, a record 7 million people were behind bars, on probation or on parole. Of the total, 2.2 million were incarcerated. The People's Republic of China ranks second with 1.5 million. The United States has 5% of the world's population and 25% of the world's incarcerated population.
Prisoners reside in different facilities that vary by security level, especially in security measures, administration of inmates, type of housing, and weapons and tactics used by corrections officers. The federal government's Bureau of Prisons uses a numbered scale from one to six to represent the security level. Level six is the most secure, while level one is the least.
State prison systems operate similar systems. California, for example, classifies its facilities from Reception Center through Levels I through IV (minimum to maximum security) to specialized high security units (all considered Level IV) including Security Housing Unit (SHU)California's version of supermaxand related units.
As a general rule, county jails, detention centers, and reception centers, where new commitments are first held either while awaiting trial or before being transferred to "mainline" institutions to serve out their sentences, operate at a relatively high level of security, usually close security or higher.
Minimum & medium Security:
Prisoners that fall into the medium security group may sleep in dormitories on bunk beds with lockers to store their possessions. They may have communal showers, toilets and sinks. Dormitories are locked at night with one or more correctional officers supervising. There is less supervision over the internal movements of prisoners. The perimeter is generally double fenced and regularly patrolled.
Prisoners in minimum security facilities are considered to pose little physical risk to the public and are mainly non-violent "white collar criminals". Minimum security prisoners live in less-secure dormitories, which are regularly patrolled by correctional officers. As in medium security facilities, they have communal showers, toilets, and sinks.
A minimum-security facility generally has a single fence that is watched, but not patrolled, by armed guards. At facilities in very remote and rural areas, there may be no fence at all. Prisoners may often work on community projects, such as roadside litter cleanup with the state department of transportation or wilderness conservation. Many minimum security facilities are small camps located in or near military bases, larger prisons (outside the security perimeter) or other government institutions to provide a convenient supply of convict labor to the institution. Many states allow persons in minimum-security facilities access to the internet.
Under close security, prisoners usually have one or two person cells operated from a remote control station. Each cell has its own toilet and sink. Inmates may leave their cells for work assignments or correctional programs and otherwise may be allowed in a common area in the cellblock or an exercise yard. The fences are generally double fences with watchtowers, housing armed guards, plus often a third, lethal-current electric fence in the middle.
In a maximum security prison or area, all prisoners have individual cells with sliding doors controlled from a secure remote control station. Often prisoners are confined in their cells 23 hours per day, but in some institutions, prisoners are allowed out of their cells for most of the day. When out of their cells, prisoners remain in the cellblock or an exterior cage. Movement out of the cellblock or "pod" is tightly restricted using restraints and escorts by correctional officers.
Supermax prison facilities provide the highest level of prison security. These units hold those considered the most dangerous inmates. These include serial killers, inmates who have committed assaults, murders or other serious violations in less secure facilities, high-profile criminals such as Theodore Kaczynski, Terry Nichols, Zacarias Moussaoui, and inmates known to be or accused of being prison gang members.
The United States Federal Bureau of Prisons operates one such facility: ADX Florence, built specifically as a supermax facility in 1994. United States Penitentiary, Marion was a supermax but has been downgraded to a medium security facility. Utilizing a penal construction and operation theory known as the "control unit" prison, the conditions of these facilities are considered harsh by some human rights watchdog organizations. Inmates generally spend 23 or more hours per day in their cells, with the additional hour spent either in a supervised one-man shower, or in an "outdoor" recreation area, generally a solid-walled pen twice the size of a cell, also used in solitary confinement.
The cells in ADX Florence minimize social contact and increase isolation between cellmates and the external prison workings. The cells, usually 3.5 x 2 meters (7 ft x 12 ft) are constructed with solid doors, with no windows and a locked food port, and are nearly completely soundproofed. Drains and drainpipes leading to the cells, which in USP Marion provided a method of communication and passage of contraband between cells, route to a central damping location. Telephone privileges are virtually non-existent, as is any access to the internet. All mail, except pre-announced legal communications, is opened, read, and censored. No physical contact is allowed with visitors. Prisoners receiving visitors are isolated in sealed compartments and speak by telephone. The windows of the cells are very small and designed to give no actual view of any other part of the prison (in order to prevent a prisoner from knowing his location and thus discouraging escape attempts). Access to ADX Florence is through a tunnel, and the prison is explicitly designed to be defensible against armed attacks from the outside.
Some prisoners at ADX Florence are part of a step-down program, where they are gradually rewarded for good behavior by being allowed more common-area interactions. These prisoners, if they complete the program, will transfer back to a maximum-security facility.
Although the U.S. federal government only operates one facility of this nature, many states are following suit by building segregation units in existing prisons or whole new facilities (such as the Ohio State Penitentiary) built on the same model.
Only persons convicted of violating Federal laws (that is, laws of the United States) are sent to Federal prisons. Some individuals awaiting trial for violating Federal laws are also held in Federal prisons. While the Federal Bureau of Prisons (Bureau) does house a few state inmates, most inmates convicted of violating state or local laws are sent to state prisons or city or county jails.