Under federal law, the attorney general can move to add, reschedule or remove drugs on his own, at the request of the health and human services secretary or in response to a public petition. But the law also requires the attorney general to gather data and scientific and medical evaluation from the HHS secretary before doing so.
Congress can pass laws to change the scheduling of drugs. Even if the attorney general does decide to move toward rescheduling, Congress can overturn his decision, experts say.
The Drug Enforcement Administration already has denied a petition to reschedule the drug, based on findings by HHS. HHS determined that marijuana has a "high potential for abuse" and "no currently accepted medical use in treatment in the United States," leading the DEA to reject the petition in 2011. The petition was filed nearly a decade earlier, in 2002.
I would add four observations. First, pot is already de facto legal, as you can find out by going to any of a zillion frat parties this weekend. Second, the incoming AG, Loretta Lynch, has said firmly that she opposes pot legalization -- a quite direct answer, given the entirety of her testimony. Third, it was several years into the present Administration that the federal government refused a request to take pot off Schedule I. Fourth, a Congress vastly more liberal than this one (2006-2010) made absolutely no move to remove pot from Schedule I.
The facts being what they are, this is not that hard to figure out, unless you're stoned.