The Drug Enforcement Administration (DEA) has rejected an appeal to declassify marijuana, but announced plans to unlock more medical research into the substance. Licenses will be given to a number of universities to cultivate the plant for research purposes. Previously, only one institution — the University of Mississippi — has been allowed to do so, creating a bottleneck for research, with scientists having to wait years to obtain federally approved samples.

"This is a good day for science," Kevin Sabet, president of Smart Approaches to Marijuana, told Reuters. "This shows that the federal government is flexible on legitimate research but is nowhere near wanting to legalize marijuana."

But marijuana remains a schedule I drug — just like heroin

Marijuana has been classified by the DEA as a Schedule I drug for nearly 50 years. This puts it in the same class as heroin and states that it has "no currently accepted medical use and a high potential for abuse." Advocates have tried to change this classification, but the US government has repeatedly rejected such appeals. The policy announced today does not remove marijuana from the list of Schedule I substances, but does open the door to finding new, practical benefits for the drug. "We are tethered to science and bound by statute," DEA spokesman Rusty Payne said Thursday.

Restrictions placed on marijuana cultivation by the federal government have hamstrung research. As of 2013, fewer than 20 randomized controlled trials (one of the highest standards in scientific research) involving around 300 patients have tested the benefits of smoked marijuana, according to the American Medical Association. This is despite the fact that research suggests marijuana can alleviate symptoms of a number of diseases, from muscle spasms in multiple sclerosis patients to anxiety in those suffering from post-traumatic stress disorder.

Some 25 states have approved the use of medical marijuana for conditions including Alzheimer’s, rheumatoid arthritis, Parkinson’s, and Crohn’s disease. This policy change from the Obama administration should provide scientists with new avenues of research to support and improve these medical applications.

Update August 11th, 12:07ET PM: Updated to include confirmation of the DEA's announcement.