Chinese labour camps, so-called "re-education through labour", is a legal practice dating from 1957 and subsequently endorsed in 1982, which is an administrative measure of compulsory educative reform which China had adopted to discourage and reduce crime and safeguard public law and order. Whilst the Chinese government emphasizes that the rights provided for under the Constitution and laws are guaranteed for the inmates in re-education facilities, it is believed that this system is widely abused to detain political prisoners without charges. The 20 million prisoners in China in 1990 produced a total output of goods and services so large that it is routinely included in the country's GNP statistics. Prisoners can also be leased as labour to any Western company wishing to open a factory in China