Where in the Constitution is the authority given to the feds to interfere in this matter?
Commerce clause of course.
To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes;
It says to regulate, not to outlaw.
It is absurd to think that the Federal Government was given the power to outlaw something that foreign Nations do. Logically, then, it cannot outlaw what the States do either based upon this clause.
ML/NJ
The Commerce Clause empowers Congress to pass a law, or not.
It does not power unelected bureaucrats to sit around writing administrative rules that have the full-force of law.