25 U.S. Code § 403c - Identity of lessor; period of lease
Such leases may be made only by the individual Indian owner of the land or by the authorized representatives of the tribe or group of Indians to whom the land belongs, subject to the approval of the Secretary of the Interior or his authorized representative. Restricted allotments of deceased Indians, when the heirs or devisees cannot agree on a lease, may be leased for them in the manner prescribed by section 380 of this title. No lease shall be made by or on behalf of any tribe for a longer period than is or may be authorized by the tribal constitution, charter, or ordinances. Nothing contained in this section or section 403b of this title shall be construed to repeal any authority to lease restricted lands which any Indian, Indian tribe, or official of the Department of the Interior would have in the absence of such sections.