The Controlled Substances Act of 1970 grants the head of the Food and Drug Administration authority to designate and remove illegal drugs from the schedules of controlled substances. The FDA can remove marijuana at any time and as long as the DEA director doesn't object, that is the law.
The DEA and FDA directors serve at the pleasure of the president. Thus, Obama can legalize marijuana if he wants to. He doesn't remotely want to.
The DEA and FDA directors serve at the pleasure of the president. Thus, Obama can legalize marijuana if he wants to. He doesn't remotely want to.