A former senior drug policy advisor to the Obama administration predicts a crackdown if state ballot initiatives legalizing marijuana pass tomorrow:

“Once these states actually try to implement these laws, we will see an effort by the feds to shut it down,” [Kevin] Sabet said. Sabet’s vision of post-election pot realities in Washington and Colorado — where Amendment 64 has majority support, according to a recent poll — seems to suggest a possible weed war between the feds and the states.

“We can only guess now what exactly that would look like,” Sabet said. “But the recent U.S. Attorney actions against medical marijuana portends an aggressive effort to stop state-sponsored growing and selling at the outset.”

C0nsider this hypothetical situation: ballot initiatives in Washington and Colorado to regulate and tax marijuana like alcohol pass tomorrow, as polls suggest they will. As the Feds consider how to respond to the states’ interposing measure, a lower level DEA or DOJ official sends out a memo indicating a willingness to compromise with the states, similar to the 2009 Ogden memo promising not to crack down on lawfully-operating medical marijuana dispensaries.

Businesses will begin to sell the drug and the state will make budgetary assumptions based on the substantial expected revenue from pot taxes. Eventually, for whatever reason–to appear tough on crime, or after realizing that selective state-by-state enforcement of drug laws is problematic–the administration realizes that this approach is untenable, and declares open season on marijuana users and purveyors.

All of a sudden the DEA starts knocking down doors in Denver or Seattle. But the targets, unlike in California (where there have been more than 800 raids this year) or other medical marijuana states, will not just be dispensaries, but an array of businesses that also sell other things. The governors will be under immense pressure to act to enforce the laws they were elected to uphold. Such action could range from publicly condemning the raids to throwing federal agents in prison: full-on nullification. That’s the “constitutional showdown” the Justice Department has warned us about.

How far states will have to go to exercise self-government depends above all on the intractability of the DEA. I have no doubt that if it actually came down to states arresting DEA agents the federal government would be forced to reevaluate. Doubling down would mean arresting the governor or invading, and that seems exceedingly unlikely.

One needn’t be a staunch proponent of states’ rights to side with them on this issue. The conflict isn’t exactly between federal and state governments per se, it’s between states and raw bureaucratic fiat. Within existing federal law the DEA has the discretionary authority to recognize pot’s medical benefits, as more than a dozen states do, and recalibrate accordingly. They haven’t. And when an unaccountable federal government fails to recognize the legitimate interests of the people, as represented by majority opinion and by duly-enacted law, shouldn’t states be next in line to protect them? Isn’t that what federalism is for?