 However, these powers were eliminated in the final version of the law, in what historian Dirk Vandewalle described as a rare example of the national interest overriding that of the provinces.Under the law, a contractor working for the National Oil Corporation is permitted to bring equipment into Libya free of import duties; however, this provision does not apply to contractors working for private oil companies, who are governed by the Administrative Contracts Regulation 2000.Amendments to the law in 1961 and 1965 altered the calculation of royalties.