So the Ninth Circuit holds today in United States v. City of Arcata:
The [Arcata, Cal. and Eureka. Cal.] ordinances purport to bar the federal government from “recruit[ing], initiat[ing] contact with for the purpose of recruiting, or promot[ing] the future enlistment of any person under the age of eighteen into any branch of the United States Armed Forces.” They also subject military recruiters to civil penalties for each infraction….
The doctrine of intergovernmental immunity arose from the Supreme Court’s decision in McCulloch v. Maryland, 17 U.S. (4 Wheat.) 316 (1819), which established that “the states have no power, by taxation or otherwise, to retard, impede, burden, or in any manner control, the operations of the constitutional laws enacted by congress to carry into execution the powers vested in the general government.” …
[T]he ordinances violate intergovernmental immunity …. First, the ordinances seek to directly regulate the conduct of agents of the federal government. As noted above, the ordinances — by their express terms — prohibit military recruiters from recruiting or attempting to recruit individuals under the age of eighteen. By constraining the conduct of federal agents and employees, the ordinances seek to regulate the government directly….
[T]he ordinances also discriminate against the United States. “The nondiscrimination rule finds its reason in the principle that the States may not directly obstruct the activities of the Federal Government.” The ordinances at issue do not affect the federal government incidentally as the consequence of a broad, neutrally applicable rule. Rather, they specifically target and restrict the conduct of military recruiters. At the same time, the ordinances state that they do not “prevent individuals who are not employed by or agents of the U.S. government from encouraging people under the age of eighteen to join the military.” A state or local law discriminates against the federal government if “it treats someone else better than it treats” the government. The cities’ differential treatment of identical conduct based on the actor’s status as a federal agent or employee fits squarely within this framework.
The cities also raise the Tenth Amendment as a defense, arguing that the ordinances represent a valid exercise of the cities’ general police powers. The Tenth Amendment provides that “[t]he powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” U.S. Const. amend. X. But regulating the federal government’s military recruitment efforts is not a power reserved to the states. The Constitution expressly provides Congress with the power to “raise and support Armies” and to “make Rules for the Government and Regulation of the land and naval Forces.” U.S. Const. art. I, § 8, cls. 12, 14. And the Supreme Court has made clear that the federal government “can determine, without question from any State authority, how the armies shall be raised.”
This strikes me as exactly correct. The federal government is acting well within its enumerated powers, and state governments and their local subdivisions may not interfere with it.