What is clear is that marijuana remains illegal under federal law. In theory an army of DEA agents could swoop down on every joint-smoker in Washington or pot-grower in Colorado and haul them off to federal court and thence to federal prison. But that would require either a huge shift in Justice Department resources or a huge increase in federal marijuana enforcement funding, or both, and neither seems likely. More likely is selective, exemplary enforcement aimed at commercial operations, said one former White House anti-drug official.