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14 remedy departures from customary international law because the Constitution deprives them of the independent power to lay imposts or duties on imports and exports, to enter into treaties or compacts, and to wage war. Compare Art. I, §10, with Declaration of Independence ¶4 (asserting the power to “levy War, conclude Peace, contract Alliances, [and] establish Commerce”); see Kansas v. Colorado, 185 U. S. 125, 143 (1902).

Article IV also imposes duties on the States not required by international law. The Court’s Full Faith and Credit Clause precedents, for example, demand that state-court judgments be accorded full effect in other States and preclude States from “adopt[ing] any policy of hostility to the public Acts” of other States. Hyatt II., 578 U. S., at ___ (slip op., at 5) (internal quotation marks omitted); see Art. IV, §1. States must also afford citizens of each State “all Privileges and Immunities of Citizens in the several States” and honor extradition requests upon “Demand of the executive Authority of the State” from which the fugitive fled. Art. IV, §2. Foreign sovereigns cannot demand these kinds of reciprocal responsibilities absent consent or compact. But the Constitution imposes them as part of its transformation of the States from a loose league of friendship into a perpetual Union based on the “fundamental principle of equal sovereignty among the States.” Shelby County v. Holder, 570 U. S. 529, 544 (2013) (emphasis in original and internal quotation marks omitted).

The Constitution also reflects implicit alterations to the States’ relationships with each other, confirming that they are no longer fully independent nations. See New Hampshire v. Louisiana, 108 U. S. 76, 90 (1883). For example, States may not supply rules of decision governing “disputes implicating the[ir] conflicting rights.” Texas Industries, Inc. v. Radcliff Materials, Inc., 451 U. S. 630, 641 (1981). Thus, no State can apply its own law to interstate disputes over borders, Cissna v. Tennessee, 246 U. S. 289,