The issue focused on whether those medical studies were performed with scientific rigor.

Kathleen Sebelius, the secretary of Health and Human Services, said that study has been completed. The research also found "no evidence" that medical marijuana will help treat cancer or HIV/AIDS, she said.

There's no science to back up claims that medical marijuana can treat diseases like AIDS, Crohn's disease and Alzheimer's disease, Sebelius said.

An academic paper written by researchers