The government will point to the Nevada Disclaimer Clause. When Congress invited Nevada to join the Union in 1864, it mandated that the Nevada constitutional convention pass an act promising that Nevada would "forever disclaim all right and title to the unappropriated public lands lying within said territory, and that the same shall be and remain at the sole and entire disposition of the United States . . ." The Nevada state constitutional convention did so.
Cliven Bundy says the Disclaimer Clause is illegal and unconstitutional. With respect to another Nevada rancher making the same claim, a federal court ruled that the Disclaimer Clause was legal and constitutional. Note I'm only saying what a federal court ruled.
The Law these days apparently speaks from the mouth of the guns of the Bureaucracies’ SWAT teams.