Embed from Getty Images

For the fourth consecutive time, the Drug Enforcement Administration has denied a petition to lessen federal restrictions on the use of marijuana.

While recreational marijuana use is legal in four states and D.C., and medical applications of the drug have been approved in many more, under federal law, it remains a Schedule 1 controlled substance, which means it's considered to have "no currently accepted medical use" and a "high potential for abuse."

The gap between permissive state laws and a restrictive federal policy has become increasingly untenable in the minds of many doctors, patients, researchers, business owners, and legislators, the Washington Post reports.

For instance, last fall, a Brookings Institution report slammed the federal government for "stifling medical research" in the area of marijuana policy. As a Schedule 1 drug, it's much harder for researchers to work with marijuana than with many other controlled substances. The American Academy of Pediatrics has called on the government to move marijuana into Schedule 2 to facilitate more research into medical uses.

The current federal status of marijuana also makes it impossible for state-legal marijuana businesses to take the same tax deductions afforded to other business, with some marijuana operations complaining that their effective tax rates are in the range of 60 percent to 90 percent, according to a Denver accountant who works with such businesses, Jordan Cornelius. Federal restrictions also make banks reluctant to work with marijuana businesses, leading many of them to become all-cash operations — with all the risks that entails.

Despite these concerns, the DEA today denied the petition, initiated by then-governors Lincoln Chafee of Rhode Island and Christine Gregoire of Washington state in 2011, to loosen restrictions on the drug. In a letter to the petitioners, acting DEA Administrator Chuck Rosenberg explained the agency's ruling and offered a full-throated defense of federal marijuana policy.

Rosenberg said according to the Food and Drug Administration, marijuana "does not have a currently accepted medical use in treatment in the United States."