why are conservatives fighting legalization?

theatlantic |  Normally, conservative states like Nebraska and Oklahoma champion state prerogatives, while progressive ones fight for federal uniformity. But this time the roles are almost perfectly reversed, with some conservative states championing federal uniformity, and progressive ones arguing for state diversity. The controversy has revealed an interesting fissure in the conservative movement, between pro-government “law and order” types, and anti-government “stay out of my life” types. The implications could go far beyond the happy Rastafarian admonition: “Legalize it, don’t criticize it.”

When state and federal laws are inconsistent, the default setting is that both are enforced, by their respective enforcers. State and federal governments are independent sovereigns whose laws operate independently on the citizens subject to them. If you have a Texas driver’s license, you can drive on highways in west Texas and run over all the lizards you want—as far as Texas is concerned. But some of those lizards are endangered species under federal law, and running them over is prohibited—as far as Congress is concerned. You can keep your license, but you may get an unpleasant visit from the U.S. Fish and Wildlife Service.

As long as citizens can comply with both sets of laws and Congress can successfully operate its own laws, there should be no conflict. But where there is a conflict, state law must give way, because the Constitution provides that federal law is the supreme law of the land. For example, when state law “stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress,” the Supreme Court has said that state law is preempted.

Does state legalization of marijuana interfere with “the full purposes and objectives of Congress” in its own prohibition of marijuana? It does, but only in a very peculiar way. And here’s where the story gets really interesting.