Attitudes about marijuana are evolving here in the U.S., but there are still concerns among health and law officials when it comes to legalization. Specifically over driving under the influence. Researchers from McLean Hospital in Massachusetts looked at the driving performance of both marijuana users and non-users, as assessed on a driving simulator. The subjects had not used marijuana for at least 12 hours. Compared to non-users, heavy marijuana users exhibited worse driving performance during the rest. Tory Spindle, Postdoctoral Research Fellow in the Department of Psychiatry and Behavioral Sciences at the Johns Hopkins University School of Medicine, joined Cheddar to discuss.