In the Indian Service Indians shall be employed as herders, teamsters, and laborers, and where practicable in all other employments in connection with the agencies and the Indian Service. And it shall be the duty of the Secretary of the Interior and the Commissioner of Indian Affairs to enforce this provision.
25 U.S. Code § 44 - Employment of Indians
For transfer of functions of other officers, employees, and agencies of Department of the Interior, with certain exceptions, to Secretary of the Interior, with power to delegate, see Reorg. Plan No. 3 of 1950, §§ 1, 2, eff. May 24, 1950, 15 F.R. 3174, 64 Stat. 1262, set out in the Appendix to Title 5, Government Organization and Employees.