The United States Supreme Court has consistently rejected claims that laws which treat Indians as a distinct class violate the equal protection rights of non-Indians.   See, e.g., Washington v. Confederated Bands and Tribes of the Yakima Indian Nation, 439 U.S. 463, 99 S.Ct. 740, 58 L.Ed.2d 740 (1979) ;  Delaware Tribal Business Comm. v. Weeks, 430 U.S. 73, 97 S.Ct. 911, 51 L.Ed.2d 173 (1977) ;  Fisher v. District Court, 424 U.S. 382, 96 S.Ct. 943, 47 L.Ed.2d 106 (1976) ;  Morton v. Mancari, 417 U.S. 535, 94 S.Ct. 2474, 41 L.Ed.2d 290 (1974).   In Morton, the Supreme Court observed:

Literally every piece of legislation dealing with Indian tribes and reservations, and certainly all legislation dealing with the [Bureau of Indian Affairs], single out for special treatment a constituency of tribal Indians on or near reservations.   If these laws, derived from historical relationships and explicitly designed to help only Indians, were deemed invidious racial discrimination, an entire Title of the United States Code (25C) would effectively be erased and the solemn commitment of the Government toward the Indians would be jeopardized.

*1159 417 U.S. at 552, 94 S.Ct. at 2483.   The Court noted the plenary power of Congress to legislate on behalf of Indians.  Id. at 551, 94 S.Ct. at 2483.   The proper inquiry in a determination of the constitutionality of such laws is whether the special treatment could be rationally tied to the fulfillment of Congress's unique obligation toward Indians.  Id. at 552, 94 S.Ct. at 2483.