The International Narcotics Control Board (INCB) is mandated by of the Single Convention to "endeavour to limit the cultivation, production, manufacture and use of drugs to an adequate amount required for medical and scientific purposes, to ensure their availability for such purposes and to prevent illicit cultivation, production and manufacture of, and illicit trafficking in and use of, drugs." The INCB administers the estimate system, which limits each nation's annual production of controlled substances to the estimated amounts needed for medical and scientific purposes.