25 U.S. Code § 194 - Trial of right of property; burden of proof
In all trials about the right of property in which an Indian may be a party on one side, and a white person on the other, the burden of proof shall rest upon the white person, whenever the Indian shall make out a presumption of title in himself from the fact of previous possession or ownership.
Source(R.S. § 2126.)
R.S. § 2126 derived from act June 30, 1834, ch. 161, § 22,4 Stat. 733.