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Rh of a trustee. In exercising its constitutionally-granted powers, the Federal Government, “following ‘a humane and self imposed policy,’ ” has committed itself to “ ‘moral obligations of the highest responsibility and trust’ ” to the Indian people. United States v. Jicarilla Apache Nation, 564 U. S. 162, 176 (2011).

Nevertheless, we have repeatedly cautioned that Congress’s Indian affairs power is not unbounded. And while we have articulated few limits, we have acknowledged what should be one obvious constraint: Congress’s authority to regulate Indian affairs is limited by other “pertinent constitutional restrictions” that circumscribe the legislative power. United States v. Creek Nation, 295 U. S. 103, 109–110 (1935); see also New York v. United States, 505 U. S. 144, 156 (1992) (“Congress exercises its conferred powers subject to the limitations contained in the Constitution”).

For example, in Seminole Tribe of Fla. v. Florida, 517 U. S. 44 (1996), we held that Congress’s power under the Indian Commerce Clause was limited by “the background principle of state sovereign immunity embodied in the Eleventh Amendment.” Id., at 72. We rejected the Tribe’s argument that Congress’s Indian affairs power could exceed other constitutional restrictions when “necessary” to “ ‘protect the tribes’ ” from state interference. Id., at 60. Foundational constitutional principles like state sovereign immunity, we observed, are “not so ephemeral as to dissipate when the subject of the suit is [in] an area, like the regulation of Indian commerce, that is under the exclusive control