For years we've been told marijuana can treat everything from anxiety to chronic pain, often with more confidence than evidence because cannabis as an illegal drug is so hard to study. Now, the U.S. is reclassifying cannabis in a way that could finally make real scientific research easier. It's moving from a Schedule I drug, alongside heroin, to Schedule III, closer to drugs like Tylenol with codeine. That change could open the door to much more real research. Dr. Margaret Haney is a neurobiology professor at Columbia University and runs its Cannabis Research Lab. For decades, she's argued marijuana has been sold as medicine without the kind of rigorous testing every other prescription drug is required to go through. Even with the limitations, her work has shown the dangers of cannabis use disorder and the impacts weed can have on the teenage brain.