The issue focused on research studies that found medical marijuana could help treat pain, seizures and post-traumatic stress disorder.

But federal researchers said they were forced to study medical marijuana after the drug was banned by Congress in 1970. It's now legal for medical use in 23 states and Washington, D.C.

In 2013, medical marijuana research studies began under a four-year study called the Research Initiative on Medical Marijuana. But researchers had to stop research because of budget cuts. The study will resume again