Washington State University researchers are developing a hand-held device that police officers can use to detect THC in breath. THC is the main psychoactive compound in marijuana.

SEATTLE -- Washington state troopers are keeping a close eye on their colleagues in Colorado who continue testing new technology aimed at keeping drivers high on marijuana off the road.

Do you get high? Do you drive? This is why you need to understand the laws behind DUI marijuana charges — and the particular science of THC, too.