Morton v. Ruiz
Plaintiff's were Native Americans who were living off of, but near, and Indian Reservation. After Plaintiff lost his job he applied for general assistance benefits from the BIA. He was told he was inelligable because he did not live on a reservation.
The court, viewing the legislative history, concludes that Congress did not intend to limit the benefits to Native Americans living on reservations. However, it notes, that an agency can still make a rule that limits the benefits to those living on a reservation. This rule must not be made ad hoc. Rather "the agency must, at a minimum, let the standard be generally known so as to assure that it is being applied consistently and so as to avoid both the reality and the appearance of arbitrary denia of benefits." The court states that ad hoc determinations are inherently arbitrary.