Yesterday a California appeals court rejected a challenge by San Diego and San Bernardino counties to a state law requiring them to issue ID cards for medical marijuana patients. The counties, which have been resisting the state policy allowing medical use of cannabis for years, argued that the Medical Marijuana Program Act of 2003, which established the current ID card system, is pre-empted by the federal Controlled Substances Act (CSA). The court disagreed:

We conclude the identification card laws do not pose a significant impediment to specific federal objectives embodied in the CSA. The purpose of the CSA is to combat recreational drug use, not to regulate a state's medical practices....

Although California's decision to enact statutory exemptions from state criminal prosecution for such persons arguably undermines the goals of or is inconsistent with the CSA—a question we do not decide here—any alleged "obstacle" to the federal goals is presented by those California statutes that create the exemptions, not by the statutes providing a system for rapidly identifying exempt individuals. The identification card statutes impose no significant added obstacle to the purposes of the CSA not otherwise inherent in the provisions of the exemptions that Counties do not have standing to challenge, and we therefore conclude the limited provisions of the MMP that Counties may challenge are not preempted by principles of obstacle preemption.

Note that the decision does not address the question of whether the CSA pre-empts the laws shielding medical marijuana users from state prosecution. In the 2005 decision Gonzales v. Raich, the U.S. Supreme Court held that the power to regulate interstate commerce permits federal prosecution of patients who possess marijuana for medical use, even in states that permit such use. But it did not say the CSA requires states to prosecute them. And the following year, in Gonzales v. Oregon, it ruled that the CSA does not bar states from allowing doctors to prescribe barbiturates for patients with terminal illnesses who want to kill themselves.

Identifying statutory exceptions that permit states to experiment with different drug policies is a poor substitute for the original constitutional design, under which Congress has no authority to override such experiments. But I suppose it's better than nothing. This way, if Congress wants to obliterate the distinction between local and national matters, dictating policy choices that the Constitution reserves to the states, it has to do so explicitly. 

The appeals court decision is here (PDF).

[Thanks to Dan Berger at the ACLU Drug Law Reform Project for the tip.]