Quick search by citation:

25 U.S. Code § 5375 - Appeals

Except as provided in section 5366(d) of this title, in any administrative action, appeal, or civil action for judicial review of any decision made by the Secretary under this subchapter, the Secretary shall have the burden of proof of demonstrating by a preponderance of the evidence—
the validity of the grounds for the decision; and
the consistency of the decision with the requirements and policies of this subchapter.