Parole is the early release of a prisoner who agrees to abide by certain conditions, originating from the French parole ("voice, spoken words" but also "promise"). The term became associated during the Middle Ages with the release of prisoners who gave their word.

This differs greatly from amnesty or commutation of sentence in that parolees are still considered to be serving their sentences, and may be returned to prison if they violate the conditions of their parole.

Alexander Maconochie, a Scottish geographer and captain in the Royal Navy, introduced the modern idea of parole when, in 1840, he was appointed superintendent of the British penal colonies in Norfolk Island, Australia. He developed a plan to prepare them for eventual return to society that involved three grades. The first two consisted of promotions earned through good behaviour, labour, and study. The third grade in the system involved conditional liberty outside of prison while obeying rules. A violation would return them to prison and they would start all over again through the ranks of the three-grade process.^[1][2] He reformed its ticket of leave system, instituting what many consider the world's first parole system.^[3] Prisoners served indeterminate sentences from which they could be released early if they showed evidence of rehabilitation^[4] through participation in a graded classification system based on a unit of exchange called a mark.^[5] Prisoners earned marks through good behavior, lost them through bad behavior,^[3] and could spend them on passage to higher classification statuses ultimately conveying freedom.^[5]

In an instance of multiple discovery, in 1846, Arnould Bonneville de Marsangy proposed the idea of parole (which he termed "preparatory liberations") to the Civil Tribunal at Reims.^[6][7]

In general, in Canada, prisoners are eligible to apply for full parole after serving one-third of their sentences.^[8] Prisoners are also eligible to apply for day parole,^[9] and can do this before being eligible to apply for full parole.

Any prisoner whose sentence is less than two years is sent to a correctional facility in the province or territory that convicted him or her, whilst anyone sentenced to serve no less than two years will be sent to a federal correctional facility and will thus have to deal with the Parole Board of Canada.^[10]

Parole is an option for most prisoners. However, parole is not guaranteed, particularly for prisoners serving life or indeterminate sentences. In cases of first-degree murder, one can apply for parole after 25 years if convicted of a single murder. However, if convicted of multiple murder (either first or second-degree), the sentencing judge has the option to make parole ineligibility periods consecutive - thereby extending parole ineligibility beyond 25 years and, in rare cases, beyond a normal life-span.^[11][12]

In China, prisoners are often granted medical parole or compassionate release, which releases them on the grounds that they must receive medical treatment which cannot be provided for in prison. Occasionally, medical parole is used as a no-publicity way of releasing an accidentally imprisoned convict.^[13][14]

The Chinese legal code has no explicit provision for exile, but often dissidents are released on the grounds that they need to be treated for a medical condition in another country, and with the understanding that they will be reincarcerated if they return to China. Dissidents who have been released on medical parole include Ngawang Chophel, Ngawang Sangdrol, Phuntsog Nyidron, Takna Jigme Zangpo, Wang Dan, Wei Jingsheng, Gao Zhan and Fang Lizhi.

Until 2001, parole in Israel was possible only after the prisoner had served two thirds of their sentence. On 13 February 2001 the Knesset passed a bill, brought forward by Reuven Rivlin and David Libai, which allowed the early release of prisoners who had served half of their prison term. The law was originally intended to help ease overcrowding in prisons.

Libertà condizionata is covered by Article 176 of the Italian Penal Code. A prisoner is eligible if he has served at least 30 months (or 26 years for life sentences), and the time remaining on his sentence is less than half the total (normally), a quarter of the total (if previously convicted or never convicted) or five years (for sentences greater than 7.5 years). In 2006, 21 inmates were granted libertà condizionata.

In New Zealand, inmates serving a short-term sentence (up to two years) are automatically released after serving half their sentence, without a parole hearing. Inmates serving sentences of more than two years are normally seen by the New Zealand Parole Board after serving one-third of the sentence, although the judge at sentencing can make an order for a minimum non-parole period of up to two-thirds of the sentence. Inmates serving life sentences usually serve a minimum of 10 years, or longer depending on the minimum non-parole period, before being eligible for parole.^[15] Parole is not an automatic right and it was declined in 71 percent of hearings in the year ending 30 June 2010.^[16] Many sentences include a specific non-parole period.

Parole in the United Kingdom was originally the bailiwick of just the Parole Board, but is now regulated by the National Offender Management Service.^[17] The conditions of release are called a licence, and parole is called released on licence. There are six standard licence conditions for most (non-life sentence) prisoners.^[18]

Sexual offenders have a seventh condition. Further "additional licence conditions" may be suggested by the Probation Service and set by prison governors.^[17] Since 2014 many of the probation and license monitoring functions have been carried out by private-sector "community rehabilitation companies" (CRCs).^[19]

Penologist Zebulon Brockway introduced parole when he became superintendent of Elmira Reformatory in Elmira, New York. To manage prison populations and rehabilitate those incarcerated, he instituted a two-part strategy that consisted of indeterminate sentences and parole releases.^[20]

In the United States, courts may specify in a sentence how much time must be served before a prisoner is eligible for parole. This is often done by specifying an indeterminate sentence of, say, "15 to 25 years", or "15 years to life". The latter type is known as an indeterminate life sentence; in contrast, a sentence of "life without the possibility of parole" is known as a determinate life sentence.^[21]

On the federal level, Congress abolished parole in the Comprehensive Crime Control Act of 1984 (Pub. L. No. 98-473 § 218(a)(5), 98 Stat. 1837, 2027 [repealing 18 U.S.C.A. § 4201 et seq.]). Federal prisoners may, however, earn a maximum of 54 days good time credit per year against their sentence (18 U.S.C.A. § 3624(b)). At the time of sentencing, the federal judge may also specify a post-imprisonment period of supervised release.^[22] The U.S. Parole Commission still has jurisdiction over parole for those prisoners convicted of felonies in the District of Columbia and who are serving their sentences there, as well as over certain federally incarcerated military and international prisoners.^[23][24]

In most states, the decision of whether an inmate is paroled is vested in a paroling authority such as a parole board. Mere good conduct while incarcerated in and of itself does not necessarily guarantee that an inmate will be paroled. Other factors may enter into the decision to grant or deny parole, most commonly the establishment of a permanent residence and immediate, gainful employment or some other clearly visible means of self-support upon release (such as Social Security if the prisoner is old enough to qualify). Many states now permit sentences of life imprisonment without the possibility of parole (such as for murder and espionage), and any prisoner not sentenced to either this or the death penalty will eventually have the right to petition for release (one state – Alaska – maintains neither the death penalty nor life imprisonment without parole as sentencing options).

Before being granted the privilege of parole, the inmate meets with members of the parole board and is interviewed, The parolee also has a psychological exam. The inmate must first agree to abide by the conditions of parole set by the paroling authority. While in prison, the inmate signs a parole certificate or contract. On this contract are the conditions that the inmate must follow. These conditions usually require the parolee to meet regularly with his or her parole officer or community corrections agent, who assesses the behavior and adjustment of the parolee and determines whether the parolee is violating any of his or her terms of release (typically these include being at home during certain hours which is called a curfew, maintaining steady employment, not absconding, refraining from illicit drug use and, sometimes, abstaining from alcohol), attending drug or alcohol counseling, and having no contact with their victim. The inmate gives an address which is verified by parole officers as valid before the inmate is released to parole supervision.

Upon release, the parolee goes to a parole office and is assigned a parole officer. Parole officers make unannounced visits to parolees' houses or apartments to check on them. During these home visits officers look for signs of drug or alcohol use, guns or illegal weapons, and other illegal activities. Should parolees start to use drugs or alcohol, they are told to go to drug or alcohol counseling and Narcotics Anonymous or Alcoholics Anonymous meetings. Should they not comply with conditions on the parole certificate (including abstention from voting) a warrant is issued for their arrest. Their parole time is stopped when the warrant is issued and starts only after they are arrested. They have a parole violation hearing within a specified time, and then a decision is made by the parole board to revoke their parole or continue the parolee on parole. In some cases, a parolee may be discharged from parole before the time called for in the original sentence if it is determined that the parole restrictions are no longer necessary for the protection of society (this most frequently occurs when elderly parolees are involved).

Service members who commit crimes while in the U.S. military may be subject to court martial proceedings under the Uniform Code of Military Justice (UCMJ). If found guilty, they may be sent to federal or military prisons and upon release may be supervised by U.S. Federal Probation officers.

The United States is the only nation in the world where parole is a politically divisive issue. According to the U.S. Department of Justice, at least sixteen states have removed the option of parole entirely, and four more have abolished parole for certain violent offenders.^[25][26] During elections, politicians whose administrations parole any large number of prisoners (or, perhaps, one notorious criminal) are typically attacked by their opponents as being "soft on crime". The U.S. Department of Justice (DOJ) stated in 2005 that about 45% of parolees completed their sentences successfully, while 38% were returned to prison, and 11% absconded. These statistics, the DOJ says, are relatively unchanged since 1995; even so, some states (including New York) have abolished parole altogether for violent felons, and the federal government abolished it in 1984 for all offenders convicted of a federal crime, whether violent or not. Despite the decline in jurisdictions with a functioning parole system, the average annual growth of parolees was an increase of about 1.6% per year between 1995 and 2002.

A variant of parole is known as "time off for good behavior", or, colloquially, "good time". Unlike the traditional form of parole – which may be granted or denied at the discretion of a parole board – time off for good behavior is automatic absent a certain number (or gravity) of infractions committed by a convict while incarcerated (in most jurisdictions the released inmate is placed under the supervision of a parole officer for a certain amount of time after being so released). In some cases "good time" can reduce the original sentence by as much as one-third. It is usually not made available to inmates serving life sentences, as there is no release date that can be moved up.

Some states in the United States have what is known as "mandatory supervision", whereby an inmate is released before the completion of their sentence due to legal technicalities which oblige the offender justice system to free them. In the federal prison system,^[27] and in some states such as Texas, inmates are compensated with "good time", which is counted towards time served. For example, if an inmate served five years of a ten-year prison term, and also had five years of "good time", they will have completed their sentence "on paper", obliging the state to release them unless deemed a threat to society in writing by the parole board. Where parole is granted or denied at the discretion of a parole board, mandatory supervision does not involve a decision making process: one either qualifies for it or does not. Mandatory supervision tends to involve stipulations that are more lenient than those of parole, and in some cases place no obligations at all on the individual being released.

In US immigration law, the term parole has two meanings related to allowing persons to enter or leave the United States without the normally required documentation.

Parole is "the agreement of persons who have been taken prisoner by an enemy that they will not again take up arms against those who captured them, either for a limited time or during the continuance of the war."^[28] The US Department of Defense defines parole more broadly: "Parole agreements are promises given the captor by a POW to fulfill stated conditions, such as not to bear arms or not to escape, in consideration of special privileges, such as release from captivity or lessened restraint."^[29]

The practice of paroling enemy troops began thousands of years ago, at least as early as the time of Carthage.^[30] Parole allowed the prisoners' captors to avoid the burdens of having to feed and care for them while still avoiding having the prisoners rejoin their old ranks once released; it could also allow the captors to recover their own men in a prisoner exchange. Hugo Grotius, an early international lawyer, favorably discussed prisoner of war parole.^[31] During the American Civil War, both the Dix–Hill Cartel and the Lieber Code set out rules regarding prisoner of war parole.^[32] Francis Lieber's thoughts on parole later reappeared in the Declaration of Brussels of 1874, the Hague Convention, and the Geneva Convention Relative to the Treatment of Prisoners of War.^[33]

In the United States, current policy prohibits US military personnel who are prisoners of war from accepting parole. The Code of the United States Fighting Force states: "I will accept neither parole nor special favors from the enemy."^[34] The position is reiterated by the Department of Defense. "The United States does not authorize any Military Service member to sign or enter into any such parole agreement."^[35]