Since 1968, American researchers have only been allowed to use cannabis from one source for research: a facility at the University of Mississippi. Scientists have not been (and still will not be) allowed to use marijuana from dispensaries even in states where the substance is legal for medical and/or adult use because marijuana is not legal at the federal level.
The DEA stated on May 14, 2021 that it would approve more growers pending final approval. The move will result in not only more marijuana for study, but more varieties of the plant that more closely approximate what people in the real world are using in legal states.
Scientists predict a boom in marijuana research that could result in new medical therapies, a rescheduling of the drug, and/or federal legalization.