While plain detention has been prison's most successfully realized purpose, it has been regarded as incidental to the more problematic goal of rehabilitation. In fact, prisons have proved to be uncongenial places for moral improvement from the beginning. Any prison will punish, since the deprivation of freedom is severe in itself. In addition, prison life is boring by definition and design. Prison overcrowding, like prison riots and nominal devotion to prison reform, has been a U.S. constant. While southern prisons are particularly overcrowded, many northern States have crowding problems of their own. Prisons are extraordinarily expensive to build and operate, but even if a State government decided to cut costs by giving inmates less food and space, the Federal judiciary's notions of decency would no longer permit them to do so. States under court orders face problems of space and have obtained needed funds for improvements, but there is a limit to how much imprisonment citizens will underwrite. Exasperation with high crime and chaotic justice has led to determinate sentencing laws which in turn mean more prison crowding. Selective incapacitation is one solution, and there is broad agreement amount experts that a large minority of people going to prison do not require such a disposition. Probation is routinely imposed as one alternative to prison, but often it is a slapdash effort and is not severe enough for some cases where heavy fines, restitution, or community service might be used.