In Board of Comm'rs of Jackson County v. United States, 308 U.S. 343 (1939), the Court held that the United States, suing on behalf of a Native American, could not recover prejudgment interest from a county even though the county had improperly collected those taxes. While noting that "interest in inter-governmental litigation has no . . . roots in history," id., at 351, the Court did not rule out the possibility that in an unusual case, considerations of fairness might make it appropriate to collect such interest from a state agency, see id., at 352.