Bureau of Alcohol, Tobacco and Firearms (ATF) director Mike Sullivan appeared Monday on Fox News to defend a memo sent gun dealers in the United States. He claimed the agency was only following laws passed by Congress.

The memo stated that those who use marijuana legally in accordance with their state’s laws cannot be sold or possess firearms.

The use of medical marijuana has been legalized in 16 states and the District of Columbia, but marijuana is currently a Schedule I drug under the federal Control Substances Act. Schedule I is the most restrictive classification, reserved drugs with a high potential for abuse and no accepted medicinal value.

"ATF is following the Gun Control Act, which indicates that anybody who is unlawfully using or addicted to any controlled substance is prohibited from purchasing a firearm," Sullivan said.

"And the last time I looked marijuana is still listed as a controlled substance by the two principle federal agencies, the FDA and DEA, and it is still a federal crime to cultivate, possess or distribute marijuana. So ATF is in compliance with the Gun Control Act and they're responding to inquires from gun dealers."

Marijuana Policy Project director of government relations Steve Fox shot back. He said that the ATF could have taken a difference stance on medical marijuana, like other federal agencies have already done under the Obama administration.

The Department of Justice announced in 2009 that the agency did not believe prosecuting medical marijuana patients was a good use of resources.

"ATF can't on their own determine and interpret Congress's intent," Sullivan responded. "Congress passed the Gun Control Act. If Steve has an issue with it, Steve should by lobbying Congress."

"This is not a policy by the ATF, and Steve knows that, this is a federal statue," he added.

But Fox said that the agency did have some leeway in interpreting the law, noting that anyone with an ongoing prescription to OxyContin or other drugs could be considered addicted to a controlled substance.

Watch video, courtesy of MPP, below: