In the United States, life imprisonment is amongst the most severe punishments provided by law, depending on the state, and second only to the death penalty. According to a 2013 study, 1 of every 2,000 inhabitants of the U.S. were imprisoned for life as of 2012[update]. Many U.S. states can release a convict on parole after a decade or more has passed, but in California, people sentenced to life imprisonment can normally apply for parole after seven years.
The laws in the United States categorize life sentences as "determinate life sentences" or "indeterminate life sentences," the latter indicating the possibility of an abridged sentence, usually through the process of parole. For example, sentences of "15 years to life," "25 years to life," or "life with mercy" are called "indeterminate life sentences", while a sentence of "life without the possibility of parole" or "life without mercy" is called a "determinate life sentence". The potential for parole is not assured but discretionary, making it an indeterminate sentence. Even if a sentence explicitly denies the possibility of parole, government officials may have the power to grant an amnesty to reprieve, or to commute a sentence to time served.