More so than Barack Obama's presidency, Eric Holder's tenure as Attorney General is proving to be an unequivocal disappointment for progressives. Holder's time in office was launched with bang. During his confirmation hearings, Holder disavowed the Bush administration's use of torture in interrogations. He was central to the administration's widely touted plans for closing the Guantanamo Bay detention facility and announced that high-profile detainees there would be tried in federal court. And he promised deference to states on medical marijuana, ending federal raids where medical marijuana was dispensed within the bounds of state law. On Guantanamo and trying detainees, Holder's about-face seemed forced. Congress overwhelmingly voted against funding alternative housing for Guantanamo detainees and public outcry was severe over Holder's announcement that federal courts could handle their trials. Yet for the Justice Department's back-pedaling from medical marijuana legalization, there is no excuse. For years, states have increasingly embraced medical marijuana legalization, generating a tension between federal law prohibiting pot production, distribution and possession, and state laws permitting it under narrow circumstances. Though George W. Bush initially campaigned in favor of deferring to state regulations -- stating, "I believe each state can choose that decision as they so choose," -- his administration was no friend to medical marijuana patients. Then-Senator Obama also promised to steer clear of crackdowns on medical marijuana operations during his run for president. Unlike Bush, however, Obama initially kept his promise. Addressing press just a month after Obama's inauguration, Holder was asked whether the raids on medical marijuana dispensaries that had thus far continued represented the administration's policy. "No," Holder asserted. "What the president said during the campaign, you'll be surprised to know, will be consistent with what we'll be doing in law enforcement. He was my boss during the campaign. He is formally and technically and by law my boss now. What he said during the campaign is now American policy." Bam. So what's up with the memos that U.S. Attorneys -- formally and technically and by law Holder's employees -- have been distributing recently indicating that state law is no barrier to federal prosecution for medical marijuana operations? The memos have already claimed at least one victim in the movement towards legalizing medical marijuana: a law passed by both houses of the Washington State legislature. Gov. Christine Gregoire vetoed the law on Friday, and Washington State is not alone in losing its courage. New Jersey is stalling implementation of its medical marijuana bill, Colorado legislators are entertaining additional restrictions, and in Montana, where federal raids were conducted last week, Gov. Brian Schweitzer just signed a bill making it more difficult for patients to access medical marijuana. So why would the Justice Department reverse course and increase its vigilance against medical marijuana operations now? Unlike Holder's policy changes on Guantanamo, there is no visible pressure from Congress or the public. Rather, medical marijuana legalization offers cash-strapped states a fresh revenue stream. It would be hard to imagine a better time to pursue medical marijuana legalization. Instead of seizing the moment, though, Holder's Justice Department is threatening entrepreneurs and even state officials with federal prosecution. States-rights boosters are generally a nasty bunch with a sordid past. From women's rights opponents, to civil rights detractors, to fans of slavery, states-rights advocates have most often found themselves on the wrong side of history. The best argument for states rights, however, is that a little breathing room permits the states to be the laboratories of democracy that they were intended to be. Medical marijuana seems like just the kind of victimless experiment that there should be room for in our democracy. Tragically, this will not be a part of Mr. Holder's already-tarnished legacy.