Neil Jessup Newton, in his Pennsylvania Law Review entry “Federal Power Over Indians:  It’s Sources, Scope, and Limitations,” discusses the plenary era (1877-1930’s) in American Indian law during which tribal sovereignty and individual Indian rights were eroded.  Several legal decisions, precedents and rules, and Congressional actions worked not to enhance the spirit of the Trust Doctrine, fleshed out of treaties by Chief Justice John Marshall in the 1830’s, but instead to marginalize indigenous peoples.  Scholars Wilkins and Lomawaima note that this inconsistency is borne out of the tension that arises when an exclusive, preemptory application of plenary power that is Constitutionally moored is juxtaposed in real-time with absolute plenary power that is not Constitutionally moored.

Some of the more egregious examples of the use of absolute plenary power included the Major Crimes Act, the short-shrift given by the courts to the Trade and Intercourse Act, and the use of the last-in-time rule by courts to effectively nullify treaty agreements.  But the most destructive role these biases played in Indian affairs during the plenary era was to deny individual Indians the basic rights afforded to citizens of the United States, including the ability to redress wrongs through the court system.  Best evidenced by cases such as Quick Bear in which American missionaries were allowed to receive salaries from Indian trust funds, Kagama in which the Court determined that Indian nations had limited authority over internal affairs, and Lone Wolf in which the last-in-time rule “permitted abrogation's of treaties.", the use of absolute plenary power successfully denuded tribes of enormous amounts of land.

In its best sense, the exclusive, preemptory power of Congress to regulate Indian affairs has thankfully precluded the government from simply overpowering tribes militarily, cajoled it into, as near as possible, upholding the spirit of Chief Justice Marshall’s and treaty-based notions of tribal sovereignty, and from robbing Native Americans in the name of commerce under the Trade and Intercourse Act.  After the vicious land grab of the 1934 Indian Reorganization Act and then the 1978 American Indian Religious Freedom Act, the Congress and courts appear to have settled into a mode of operation that “precludes (the) extension of State law” into Indian Country.  Cases like Morton v Mancari and Mclanahan v Arizona State, in which it was decided that Indian workers on reservation lands cannot be taxed by the State, stand as examples of a new era in Congressional application of plenary power.

References

Newton, Nell Jessup. "Federal Power over Indians: Its Sources, Scope, and Limitations." University of Pennsylvania Law Review. vol. 132, ed. 2. 1984.

Wilkins, David E., and K. Tsianina Lomawaima. Uneven Ground: American Indian Sovereignty and Federal Law. Norman, Oklahoma. University of Oklahoma. 2001.