Senator Rubio recently reiterated that he would enforce federal laws against marijuana – even in states that have legalized the practice.

I think he’s right that federal laws should be enforced so long as they are constitutional. And the view that federal anti-marijuana laws are constitutional is a reasonable one. But I also think a change in federal law would be preferable to enforcement in this instance. Reihan Salam and I wrote about this issue in NR recently:

In Gonzales v. Raich, the Supreme Court ruled that Congress had the power to criminalize the local cultivation and use of marijuana under the commerce clause even if state law authorized it. In his concurring opinion, Justice Antonin Scalia observed that Congress has the power to regulate in-state activities that do not have an impact on interstate commerce when doing so is “necessary to make a regulation of interstate commerce effective.” But what if regulating in-state activities is not necessary to achieve this goal? Recently, William Baude, a law professor at the University of Chicago, has argued that constitutional doctrine should recognize that though Congress has the right to regulate interstate commerce, it can regulate in-state commerce only insofar as doing so is essential to achieving a legitimate constitutional purpose. One could argue that the failure to regulate in-state commerce in marijuana will lead to negative spillover effects that cross state borders. If a state can demonstrate that it is capable of regulating its in-state marijuana market effectively, however, the justification for federal interference is greatly weakened.
With this principle in mind, Congress could pass a law formally declaring that the federal government would recognize the legal status of marijuana businesses under state law as long as in-state marijuana markets met certain requirements. The same principle could extend to other policy questions as well, such as the federal role in establishing a minimum drinking age. If a state moves to lower its drinking age while pursuing various other steps that would reduce the [cross-state] harms associated with alcohol consumption, should the federal government try to make states keep their minimum drinking age at 21? By limiting federal interference in the regulation of in-state markets to what is strictly necessary to achieve legitimate constitutional purposes, we will foster more creativity and experimentation at the state level.

(disclosure)