Marijuana Laws and the Supremacy Clause

[SteveRogers]

To be clear, mere legalization of marijuana by a state does not in any way violate the Supremacy Clause. Yes, the federal law making marijuana illegal is the supreme law of the land. But like any other federal law, the federal government cannot order state authorities to enforce it. So there's nothing unconstitutional about a state taking its own laws criminalizing possession of marijuana off of its books.

The slightly better version of the argument is that when a state not only decriminalizes marijuana but also enacts a comprehensive scheme regulating and taxing marijuana, that scheme undermines the federal regulatory scheme designed to prohibit marijuana and therefore the state regulations are preempted by federal law. Nebraska and Oklahoma tried to make a version of this argument in their suit against Colorado, but SCOTUS through out the case without giving an opinion.