Imprisonment in law is the specific state of being physically incarcerated or confined in an institutional setting such as a prison. Courts of the United States, including the U.S. Supreme Court, have recognized that the minimum period in an indeterminate sentence that was actually imposed by a court of law is the official term of imprisonment. In other words, any "street time" that was ordered by the court as part of the defendant's punishment does not constitute term of imprisonment.
Imprisonment in other contexts is the restraint of a person's liberty, for any cause whatsoever, whether by authority of the government, or by a person acting without such authority. The latter case constitutes "false imprisonment". Imprisonment does not necessarily imply a place of confinement but may be exercised by any use or display of force, lawfully or unlawfully. People become prisoners, wherever they may be, by the mere word or touch of a duly authorized officer directed to that end.
Sometimes gender imbalances occur in imprisonment rates, with incarceration of males proportionately more likely than incarceration of females. Ethnic minorities can also contribute disproportionate numbers to prison populations.


England and Wales

s and army soldiers have been imprisoned throughout history. In English law, imprisonment is the restraint of a person's liberty. The 17th century book Termes de la Ley contains the following definition:
This passage was approved by Atkin and Duke LJJ in Meering v Grahame White Aviation Co. It is not imprisonment to prevent a person from proceeding along a particular way if it is possible for him to reach his intended destination by another route. Imprisonment without lawful cause is a tort called false imprisonment.

United States

In the law of the United States, imprisonment does not include the period of probation, parole, or supervised release. For purposes of the Immigration and Nationality Act, every "reference to a term of imprisonment or a sentence... is deemed to include the period of incarceration or confinement ordered by a court of law regardless of any suspension of the imposition or execution of that imprisonment or sentence in whole or in part." This makes the word "sentence" and the phrase "term of imprisonment" synonymous.
Some legal experts have claimed that when a court modifies the original sentence due to probation violation, the resulting sentence counts for INA purposes. But this premise conflicts with the plain language of the U.S. Congress, which had long stated that "the maximum penalty possible for the crime... did not exceed imprisonment for one year and, if the alien was convicted of such crime, the alien was not sentenced to a term of imprisonment in excess of 6 months ."
The aforementioned phrase "maximum penalty possible for the crime" generally refers to the lower portion of every sentence that was imposed under the guidelines. For example, if a person is convicted of a Pennsylvania misdemeanor and sentenced to 4 to 23 months of imprisonment, he or she has actually been sentenced to only 4 months of imprisonment for INA purposes. And if such person's minimum sentence was within the "standard range" of 0-11 months then his or her offense is obviously not punishable by one year or more of imprisonment. Everything to the contrary leads to absurdity and deprivation of rights under color of law. It is also important to note that for deportation purposes, a criminal alien must be rearrested and taken into custody of the U.S. Immigration and Customs Enforcement after his or her term of imprisonment has been completed.