Rep. Steve Cohen (D-Tenn.) on Tuesday introduced a new bill that would let the White House drug czar study the issue of legalizing marijuana for medical purposes, something it is currently unable to do under federal law.

Cohen's bill is part of the increasingly popular call for the federal government to decriminalize marijuana possession, to compliment the decision of some states to allow the plant to be used for medical purposes.

Cohen's bill is aimed at creating more flexibility at the Office of National Drug Control Policy (ONDCP). The law creating the ONDCP says the director "shall ensure that no Federal funds appropriated to the Office of National Drug Control Policy shall be expended for any study or contract relating to the legalization (for a medical use or any other use)" of marijuana or other substances listed in Schedule 1.

The director must also "take such actions as necessary to oppose any attempt to legalize the use" of those substances.

Cohen's bill would remove this language from current law. In a hearing last week, Cohen told ONDCP Deputy Director Michael Botticelli that his office should be allowed to take these basic steps.

"I am troubled that not only is the ONDCP the only federal office required by law to oppose rescheduling marijuana even if it is proven to have medical benefits, but that the office also is prohibited from studying if that could be even be true," Cohen said. "The ONDCP's job should be to develop and recommend sane drug control policies, not be handcuffed or muzzled from telling the American people the truth."

An aide to Cohen said the bill does not require the ONDCP to make a certain finding and, instead, only gives the office the flexibility to examine the issue.

"We're not dictating what the answer should be," he said. "We're just saying Congress shouldn't put its thumb on the scale."

The ONDCP is part of the Executive Office of the President, and was created in 1988. The office coordinates drug-control efforts across the government and sets the federal government's strategy for reducing the manufacture, sale and use of illegal drugs.

On Wednesday, Cohen signed a letter with 17 other members of the House calling on President Obama to take marijuana off schedule I list of controlled substances.

In 2013, Cohen signed onto a bill from Rep. Jared Polis (D-Colo.) that would decriminalize marijuana and regulate it through a new Bureau of Alcohol, Tobacco, Marijuana and Firearms.