Recreational use of marijuana has been legal in California since January, but traffic laws are lagging.
While current sobriety tests can detect the presence of marijuana in the driver's system, they can't test for impairment.
To address the problem, the state legislature is funding a UC San Diego study that will determine how pot affects driving performance and how soon after smoking pot is it safe to drive.
LINK: Sign up to participate in the study
Researchers are recruiting 180 people for the study.