The head of the Colorado Department of Revenue has written a letter to the Drug Enforcement Administration asking that federal controls on marijuana be loosened slightly to account for its “potential medicinal value.”

Colorado is the third state with a medical-marijuana program to ask the DEA to reschedule marijuana. But Revenue Department Executive Director Barbara Brohl’s letter, written Dec. 22, does not come as a surprise. A law passed last year in the legislature required the state to ask for rescheduling by the end of this year.

In the letter, Brohl details briefly Colorado’s regulations for medical-marijuana sellers and argues that current federal law, under which all marijuana possession and distribution is illegal, make it difficult for her to administer Colorado’s laws.

“As long as there is divergence in state and federal law, there is a lack of certainty necessary to provide safe access for patients with serious medical conditions,” Brohl wrote.

The letter asks that the DEA consider moving marijuana from schedule I — a category that includes such drugs as heroin and LSD that are not considered to have medicinal value — to schedule II. Drugs in that category, such as methadone and cocaine, are considered to have some medicinal value but also be highly addictive.

Schedule II substances are able to be prescribed by doctors but are still subject to strict controls. It is unclear whether Colorado’s medical-marijuana laws — which allow doctors to authorize marijuana use through recommendation and allow patients to grow their own cannabis plants — would clash with those controls.

Earlier this year, the governors of Rhode Island and Washington also asked the DEA to reschedule marijuana. The DEA has in the past rejected similar requests to reclassify the substance.

John Ingold: 303-954-1068 or jingold@denverpost.com.