As the Tenth Amendment confirms, all legislative power not conferred on Congress by the Constitu tion is reserved for the States. Absent from the list of conferred powers is the power to issue direct orders to the governments of th e States. The anticommandeering doctrine that emerged in New York v. United States, 505 U. S. 144, and Printz v. United States, 521 U. S. 898, simply represents the recognition of this limitation. Thus, “Congress may not simply ‘com- mandeer the legislative process of the States by directly compelling them to enact and enforce a federal regulatory program.’ ” New York, supra , at 161. Adherence to the anticommandeering principle is im- portant for several reasons, including, as significant here, that the rule serves as “one of the Constitu tion’s structural safeguards of lib- erty,” Printz, supra , at 921, that the rule promotes political accountability, and that the rule prevents Congress from shifting the costs of regulation to the States.