Imprisonment as punishment for crimes was first used during the sixteenth century in Europe. Prior to that, criminal correction usually consisted of enslavement or swift physical punishment such as whipping or execution. Prison was conceived as a more humane response to criminal behavior. When Europeans established colonies in America in the seventeenth century they continued the practice of imprisoning those convicted of crimes. During the colonial era, the number of Americans in prison made up a small, barely noticeable segment of the population. That situation has changed dramatically, however. According to statistics from the Department of Justice's Bureau of Justice, if incarceration rates continue unchanged, 1 out of every 20 Americans alive today will be imprisoned at some time in their lives.

This rate of incarceration has increased quite recently. In 1980, 139 of every 100,000 Americans were incarcerated; in 1996, that number had nearly quadrupled to 427 per 100,000, according to Bureau of Justice statistics...