There are many states in the United States where a convict can be released on parole after a decade or more has passed. For example, sentences of "15 years to life" or "25 years to life" may be given; this is called an "indeterminate life sentence'", while a sentence of "life without the possibility of parole" is called a "determinate life sentence". Even when a sentence specifically denies the possibility of parole, government officials may have the power to grant amnesty or reprieves, or commute a sentence to time served.
Reacting to the squalor in the penitentiaries, another wave of reform swept the country in the 1860. Reformation replaced penitence as the key word in American penology. Prisoners were to be held only until the institution had done its job, until the prisoner had been reformed. The concepts of parole and indeterminate sentencing were regarded as forward looking in the 1870s. However, crime was not eradicated. Reformatories had the same problems of political appointment and underfunding. A problem turned out to be indeterminate sentencing. Prisoners quickly found that if they could learn to beat the system they stood a better chance of winning parole. Beating the system was not difficult: say the kind of words wardens and parole boards wanted to hear, act like the kind of person they wanted to see, hide anger and resentment behind a facade of genuine reform—this, inmates discovered, was the surest path to early freedom. No wonder so many of them were soon back in custody. Another problem with indeterminate sentencing was that prison authorities also learned to twist it to their advantage, The authorities did not hesitate to deny parole, even to those who deserved it, if they thought doing so would serve their own purposes.
But the biggest cause of the reformatories' failure to live up to expectations was a matter of attitude. Despite the enthusiasm reformers felt for indeterminate sentencing and for prison education and job-training programs, despite Brockway's stirring call for an end to vengeance in criminal justice, the people inside each prison—inmates and guards alike—never stopped seeing prison as a place of retribution.
In 1954, Master Sergeant Maurice L. Schick was convicted by a military court-martial in the brutal murder of an eight-year old girl, and sentenced to death, the ultimate penalty. Six years later, the case was forwarded to Pres. Eisenhower for final review, and he commuted his sentence to confinement at hard labor for the term of his natural life, on the express condition that he "shall never have any rights, privileges, claims or benefits arising under the parole and suspension or remission of sentence laws of the United States . . ." Sgt. Schick began a legal challenge in 1971 which eventually reached the Supreme Court, questioning the constitutionality of his punishment: Life Imprisonment Without Parole. The court decided that to be so sentenced was constitutional, though Schick's sentence was given only cursory mention. Schick's ultimate fate is unknown though, had he been given an ordinary life sentence, he would have been eligible for parole in 1969.
Despite the Schick opinion's lack of thorough analysis regarding LWOP [Life-Without-Parole], an imposing amount of precedent has developed based upon it. After Furman v. Georgia, which put the constitutionality of the death penalty in question, LWOP received increased attention from lawmakers and judges as an alternative to the death penalty.
Such penalties have been imposed before. One early American case was Ex Parte Wells. Wells was convicted of murder in 1851, and sentenced to be hanged. On the day of his execution, President Fillmore gave him a conditional pardon, and commuted his sentence to "imprisonment for life in the penitentiary at Washington." Wells appealed the conditionality of his pardon. The sentence was upheld, with no discussion by the majority of the purpose of the substituted punishment.
Although sentence vary for each state, generally the life imprisonment sentences are mandatory sentence for first degree murder in states without the death penalty and the alternative sentence in states that have the death penalty and in federal and military courts.
A 2005 survey by The New York Times found that about 132,000 of the nation's prisoners, or almost 1 in 10, are serving life sentences. In 1993, the Times survey found, about 20 percent of all lifers had no chance of parole. By 2004, the number rose to 28 percent.  As a result the United States is now housing a large and permanent population of prisoners who will die of old age behind bars. At the Louisiana State Penitentiary in Angola, for instance, more than 3,000 of the 5,100 prisoners are serving life without parole, and most of the rest are serving sentences so long that they cannot be completed in a typical lifetime. About 150 inmates have died there in the last five years.
Under the federal criminal code, however, with respect to offenses committed after December 1, 1987, parole has been abolished for all sentences handed down by the federal system, including life sentences, so a life sentence from a federal court will result in imprisonment for the life of the defendant, unless a pardon or reprieve is granted by the President.
Under some "three-strikes laws", a broad range of crimes, ranging from petty theft to murder, can serve as the triggering crime for a mandatory or discretionary life sentence in California. Notably, the U.S. Supreme Court on several occasions has upheld lengthy sentences for petty theft including life with the possibility of parole and 50 years to life, stating that neither sentence conflicted with the ban on "cruel and unusual punishment" in the Eighth Amendment to the United States Constitution.