Where life imprisonment is a possible sentence, there may also exist formal mechanisms for requesting parole after a certain period of prison time. This means that a convict could be entitled to spend the rest of the sentence (until that individual dies) outside prison. Early release is usually conditional on past and future conduct, possibly with certain restrictions or obligations. In contrast, when a fixed term of imprisonment has ended, the convict is free. The length of time served and the conditions surrounding parole vary. The date when a convict is eligible for parole does not necessarily predict when or if parole will be granted. In most countries around the world, a person granted parole after being sentenced to life imprisonment must remain parole and be subject to electronic tagging or monitoring for the remainder of their natural lives.
Some technically finite sentences handed out, in particular the United States, exceed the human maximum life span and are therefore seen as de facto life sentences. Additionally, for particularly heinous crimes, courts will sometimes add additional years onto the life sentence in order to ensure that no amount of good behavior could ever result in the person being set free. For example, Ariel Castro, who kidnapped Michelle Knight, Amanda Berry, and Gina DeJesus from the streets of Cleveland, was sentenced in 2013 to "life, plus 1,000 years" for the 937 criminal counts including kidnapping, rape, and murder. Courts in South Africa have handed out at least two sentences that have exceeded a century (to Moses Sithole, whose sentence exceeds two millennia, and Eugene de Kock). In Tasmania, Australia, Martin Bryant, the perpetrator of the Port Arthur massacre in 1996, received 35 life sentences, plus 1,035 consecutive years, all to run concurrently and for the term of his natural life.
Few countries allow for a minor to be given a lifetime sentence with no provision for eventual release; these include Antigua and Barbuda, Argentina (only over the age of 16), Australia, Belize, Brunei, Cuba, Dominica, Saint Vincent and the Grenadines, the Solomon Islands, Sri Lanka, and the United States. According to a University of San Francisco Law School study, only the U.S. had minors serving such sentences in 2008. In 2009, Human Rights Watch estimated that there were 2,589 youth offenders serving life sentences without the possibility for parole in the U.S. The United States leads in life sentences (both adults and minors), at a rate of 50 people per 100,000 (1 out of 2,000) residents imprisoned for life.
Mugshot of Burton Phillips, sentenced to life imprisonment for bank robbery, 1935
Graham v. Florida was a significant case in juvenile justice. In Jacksonville, Florida, Terrence J. Graham tried to rob a restaurant along with three adolescent accomplices. During the robbery, one of Graham's accomplices had a metal bar that he used to hit the restaurant manager twice in the head. Once arrested, Graham was charged with attempted armed robbery and armed burglary with assault/battery. The maximum sentence he faced from these charges was life without the possibility of parole, and the prosecutor wanted to charge him as an adult. During the trial, Graham pleaded guilty to the charges, resulting in three years of probation, one year of which had to be served in jail. Since he had been awaiting trial in jail, he already served six months and therefore was released after six additional months.
Within six months of his release, Graham was involved in another robbery. Since he violated the conditions of his probation, his probation officer reported to the trial court about his probation violations a few weeks before Graham turned 18 years old. It was a different judge presiding over his trial for the probation violations a year later. While Graham denied any involvement of the robbery, he did admit to fleeing from the police. The trial court found that Graham violated his probation by "committing a home invasion robbery, possessing a firearm, and associating with persons engaged in criminal activity", and sentenced him to 15 years for the attempted armed robbery plus life imprisonment for the armed burglary. The life sentence Graham received meant he had a life sentence without the possibility of parole, "because Florida abolished their parole system in 2003".
Graham's case was presented to the United States Supreme Court, with the question of whether juveniles should receive life without the possibility of parole in non-homicide cases. The Justices eventually ruled that such a sentence violated the juvenile's 8th Amendment rights, protecting them from punishments that are disproportionate to the crime committed, resulting in the abolition of life sentences without the possibility of parole in non-homicide cases for juveniles.
In 2012 the Supreme Court ruled in the case of Miller v. Alabama in a 5–4 decision and with the majority opinion written by Associate Justice Elena Kagan that mandatory sentence of life in prison without parole for juvenile offenders are unconstitutional. The majority opinion stated that barring a judge for considering mitigating factors and other information, such as age, maturity, and family and home environment violated the Eighth Amendment ban on cruel and unusual punishment. Sentences of life in prison without parole can still be given to juveniles for aggravated first-degree murder, as long as the judge considers the circumstances of the case.