1. Its actual or relative potential for abuseAnd even if it's moved to a lower schedule, it doesn't mean weed will start falling from the sky. After all, meth — NOT EVEN ONCE — is considered a Schedule II substance. Plus, as Vox notes, "Anything the agency comes up with will need to go through the National Institute on Drug Abuse (NIDA), the Department of Health and Human Services (HHS), and DEA before it gets final approval."
2. Scientific evidence of its pharmacological effect, if known
3. The state of current scientific knowledge regarding the drug or other substance
4. Its history and current pattern of abuse
5. The scope, duration, and significance of abuse
6. What, if any, risk there is to the public health
7. Its psychic or physiological dependence liability
8. Whether the substance is an immediate precursor of a substance already controlled under this subchapter
To date, NIDA has conducted about 30 studies on the potential benefits of marijuana. Since 2003, it has approved more than 500 grants for marijuana-related studies, with a marked upswing in recent years, according to McClatchy. In 2003, 22 grants totaling $6 million were approved for cannabis research, McClatchy reported. In 2012, that number had risen to 69 approved grants totaling more than $30 million.