Amendment X "The 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."
It is tortured interpretation that we can not let stand. It is time to start having the States ignore stuff. Nullification first. Succession next if needed.
We are the United States. If New York and California want to arrest or enslave their people, that is not my problem. Get out while you can or go if that is your thing
Article 4, Sec. 4
It is the duty of our federal government to protect our borders from invasion.
But no armed invasion is happening. So the state can put up a wall to encourage people crossing the border in legal places. It is illegal to cross the border at random places and trespass on state, federal and private property.
"The United States shall guarantee to every State in this Union a Republican Form of Government, and shall protect each of them against Invasion; and on Application of the Legislature, or of the Executive (when the Legislature cannot be convened) against domestic Violence."