There are three theories that Congress uses as the justification to interfere with Indian rights to sovereignty;

(1) the political question doctrine - where the political nature of the Indian nations and the US and the questions that arise are to be decided by the legislative or executive branches of the government rather than the courts. For example see: Lone Wolf v. Hitchcock, 187 U.S. 553 (1903); United States v. Kagama, 118 U.S. 375, S.Ct. 1109 (1886); where the Indians challenged an act of Congress which was passed in violation of a prior treaty with the Indian nation. The court upheld the law by stating that the power of Congress over Indian affairs was "absolute" and would not be reviewed by the federal courts because of the 'political nature' of the relationship between the Indian nation and the US.

(2) the guardian-ward relationship; here the courts have used the guardian-ward relationship or the other term used is the 'federal trust responsibility' to justify Congressional power in Indian affairs. This responsibility supposedly allows Congress extraordinary power to take actions to "protect" Indian nations.

(3) the plenary power of Congress; relying on interpretation of the constitutional provisions of

(a) the power to regulate commerce with Indian nations;

(b) the power to ratify treaties with other governments;

(c) the power to make war;

(d) the power to provide for the general welfare;

(e) the power to admit new states into the union, which also includes the power to specify the conditions upon which new states will be admitted;

(f) the power over federal territories.

The courts have said that the power of Congress in Indian affairs is plenary (full and complete). Under present law, Congressional power in Indian affairs is great but it is not absolute. See; Delaware Tribal Business Comm. V. Weeks, 97 S.Ct. 911, 918 (1977). Nor could it be, because to some extent the doctrines of plenary power of Congress and inherent sovereignty of Indian nations are mutually exclusive. We have seen that one of the most basic principals underlying the rights and powers of Indian nations is that they retain all those original sovereign powers which have not been given up or taken away.

The law is clear that an Indian nation possesses all the inherent powers of any sovereign nation except as those powers may have been qualified or limited by treaties, agreements, or specific acts of Congress. Handbook of Indian Law, p. 123. A.I.P.R.C., Commission Report, Chapter 3. Courts have held that the intent of Congress to limit the sovereign powers of Indian governments by legislation must be clearly expressed in the law in order to be effective. See; Menominee Tribe v. United States, 391 U.S. 404 (1968).