Why It's Hard To Test Whether People Are Driving While Stoned

In November, five states will vote on whether to legalize recreational use of marijuana. Four more states vote on legalizing medical marijuana, which is already legal in 25 states.

As more states are relaxing their marijuana laws, they have to deal with the issue of driving buzzed — and how to test drivers for marijuana use.

Here & Now's Jeremy Hobson talks about the challenges of marijuana testing with Marilyn Huestis, of Huestis and Smith Toxicology.

Marilyn Huestis, president of Huestis and Smith Toxicology, former investigator at the National Institute on Drug Abuse and an adjunct professor at the University of Maryland School of Medicine.