If Obama really believes what he says, though, merely doing nothing is not quite enough. Getting any change in federal law through Congress is utterly beyond hope -- even with 58 percent of Americans now favoring legalization of cannabis, according to Gallup. But he has some presidential authority that, unlike most of his powers, is just sitting there collecting dust.
The most obvious thing he could do is to remove the barriers to scientific research on the therapeutic use of marijuana. Anyone who wants to do such studies now faces two major hurdles: getting cannabis from the National Institute on Drug Abuse, the only approved source, and getting permission from the Drug Enforcement Administration and other agencies with a history of resistance.
Scientists say the federal weed is not good enough to be used in clinical studies. So Lyle Craker, a professor of plant sciences at the University of Massachusetts Amherst, applied in 2001 for permission to cultivate his own supply for medical research. In 2007, a federal administrative law judge ruled that allowing Craker to grow it "would be in the public interest." DEA, however, refused.
Craker is still waiting, 13 years later. So are patients who could benefit from more information about whether cannabis can cure them -- or, for that matter, harm them.
Obama could order the DEA to let him proceed. He also could insist that the agency license other private production of cannabis for research. He could scrap the requirement that the Public Health Service approve all privately funded research on marijuana -- a rule that, as Rick Doblin of the Multidisciplinary Association for Psychedelic Studies notes, doesn't apply to other drugs, including LSD and Ecstasy.
The president could make changes like these with zero political risk. No one expects him to sue for peace in the war on drugs. But he's begun a retreat that shouldn't stop now.