Prevailing theories about human behavior, the causes of crime and ideology about how to address criminal behavior have always influenced how and why society uses prisons. Prisons are intended to meet a variety of social goals, including incapacitation, deterrence, discipline, punishment or retribution, and rehabilitation or reformation. Some have argued that public prisons are better at all of the above while most support private prisons. The term prison privatization commonly refers to the policy of contracting out the management and operation of prisons and jails to private, for-profit companies. Prison privatization is a controversial issue, with ongoing debate over the ethics of delegating the punishment function of the criminal justice system to private actors, weather private prisons cost less to operate than public facilities, and if the quality of security and conditions of confinement differ between public and private prisons. In 2005, approximately 200 private correctional facilities operated in the United States, housing a total of 107,000 inmates. Four companies provide more than 90 percent of private prison capacity. About 6 percent of all state inmates and 14 percent of federal inmates are incarcerated in privatized facilities. The idea of privatizing prisons emerged in the 1980s as a policy remedy to the problem of growing incarceration rates, severe prison overcrowding, and constraints on increasing government funding of new prison space. Public investment in new prisons climbed eightfold from the late 1970s to the early 1990s, but was at or approaching its limits in many jurisdictions due to voter rejection of construction bonds, statutory ceilings on state debt, or general taxpayer unwillingness to support increases in government spending. With privatization used as a way of reducing costs and increasing capacity in other areas of government