In a new Rolling Stone piece on "Obama's Pot Problem," Tim Dickinson observes that it is entirely in the president's power to refrain from interfering with marijuana legalization in Colorado and Washington:

If Obama were committed to drug reform—or simply to states' rights—he could immediately end DEA raids on those who grow and sell pot according to state law, and immediately order the Justice Department to make enforcement of federal marijuana laws the lowest priority of U.S. attorneys in states that choose to tax and regulate pot.

That probably won't happen, Dickinson says:

Privately, both drug reformers and drug warriors believe the Obama administration is likely to take Colorado and Washington to court to keep them out of the pot business.

But neither Colorado's Amendment 64 nor Washington's Initiative 502 requires the state to get into the pot business, and this is no small detail. As I explained last month, both initiatives were written to specify the circumstances under which people will be exempt from state penalties for growing, possessing, and selling marijuana—something states indisputably have the power to do. State officials will not be involved in growing, selling, or even handling marijuana; they will merely certify when growers and sellers have met the conditions to avoid prosecution under state law. Those growers and sellers will still be vulnerable to federal prosecution, however. Because Dickinson elides this distinction, he exaggerates the chances that the Justice Department could persuade the courts to rule that the federal Controlled Substances Act (CSA) prevents Colorado and Washington from legalizing the commercial production and distribution of marijuana:

Unfortunately for drug reformers, the administration appears to have an open-and-shut case: Federal law trumps state law when the two contradict. What's more, the Supreme Court has spoken on marijuana law: In the 2005 case Gonzales v. Raich contesting medical marijuana in California, the court ruled that the federalgovernment can regulate even tiny quantities of pot—including those grown and sold purely within state borders—because the drug is ultimately connected to interstate commerce.

In Raich the Supreme Court held only that the federal government can continue to enforce its ban on marijuana in states that allow medical use of the plant. That does not mean the feds can compel states to help them, let alone force them to enact or maintain their own bans. And contrary to Dickinson's implication, pre-emption by the CSA requires more than the sort of "contradiction" you have when a state chooses not to punish people for activities that the federal government continues to treat as crimes. It requires "a positive conflict" between state and federal law such that "the two cannot consistently stand together." The Supreme Court has said a positive conflict exists "when it is impossible to comply with both state and federal law." That is clearly not the case here, since anyone in Colorado or Washington can comply with both state and federal law simply by staying away from marijuana.

It is notable that in the 16 years since states began legalizing marijuana for medical use, the Justice Department has never tried to overturn those laws in court with a pre-emption argument, even though it has interfered with the distribution of cannabis to patients (which began in yet another state yesterday) in many other ways. Perhaps that is because, contrary to what Dickinson says, a pre-emption argument would be anything but an "open-and-shut case." Last month Alex Kreit, a professor at the Thomas Jefferson School of Law who has studied the issue, told the Drug War Chronicle "opponents of these laws would love nothing more than to be able to preempt them, but there is not a viable legal theory to do that." Yesterday The New York Times noted that Gregory Katsas, who headed the Justice Department's civil division in George W. Bush's administration, likewise "was skeptical that a pre-emption lawsuit would succeed."

The Justice Department may be mulling a lawsuit, and it may, as Dickinson's sources suggest, end up filing one. But that does not mean it will win.

A brief co-authored by Kreit addresses the pre-emption issue in more detail.