For a century and a half, the Supreme Court was faithful to a set of foundation principles respecting Indian tribal sovereignty. Though the United States can abrogate tribal powers and rights, it can only do so by legislation. Accordingly, the Court has protected reservations as enclaves for Indian self-government, preventing states from enforcing their laws and taxes, and holding that even federal laws could not be applied to Indians without congressional permission. Recently, however, the Court has assumed the job it formerly conceded to Congress, considering and weighing cases to reach results comporting with the Justices\u27 subjective notions of what the Indian jurisdictional situation ought to be. This new subjectivist approach, the a...