President Obama is accused of lying about federal laws regarding marijuana.

In the interview, Obama was asked to reconcile his statement, as a presidential candidate, that he would not use "Justice Department resources to try to circumvent state laws [on medical marijuana]," with his administration's recent severe crackdown on medical marijuana dispensaries.

What I specifically said was that we were not going to prioritize prosecutions of persons who are using medical marijuana," Obama told Rolling Stone

The president continued, "I can't nullify congressional law. I can't ask the Justice Department to say, 'Ignore completely a federal law that's on the books.'"

But Walker isn't buying it. He notes that the Controlled Substance Act, which governs marijuana use, allows the president to, without Congressional approval, change the classifications of drugs covered under the act.

Though marijuana is currently not classified as having any medical uses, Walker writes that "Obama can instruct the relevant agencies under him to take an honest look at the research and reschedule marijuana so it qualifies as having legitimate medical uses."

Salon columnist Glenn Greenwald writes that Obama's picked an odd time to espouse the virtues of the rule of law:

The same person who directed the DOJ to shield torturers and illegal government eavesdroppers from criminal investigation, and who voted to retroactively immunize the nation’s largest telecom giants when they got caught enabling criminal spying on Americans, and whose DOJ has failed to indict a single Wall Street executive in connection with the 2008 financial crisis or mortgage fraud scandal, suddenly discovers the imperatives of The Rule of Law when it comes to those, in accordance with state law, providing medical marijuana to sick people with a prescription.

The Rolling Stone interview comes shortly after Democratic and Republican politicians from five states wrote a letter to Obama demanding that the feds back off of medical marijuana.

"We call on the federal government not to interfere with our ability to control and regulate how medical marijuana is grown and distributed," the letter states. "Let us seek clarity rather than chaos. Don’t force patients underground, to fuel the illegal drug market."