Scientists and law enforcement are inching closer to a functional breathalyzer for THC. The “potalyzer” is currently being perfected by researchers at Stanford University, according to The Mercury News.

The new gadget is easy to use and can attach to a smartphone or laptop to give results within three minutes. The potalyzer requires a saliva sample on a cotton swab, which is then analyzed by the device using the same magnetic nanotechnology employed to screen for cancer.

“Researchers… have zeroed in on saliva because testing it is less invasive and because THC in saliva may correlate with impairment better than THC in urine or blood,” read a news release from Stanford University.

California will have a legal limit for driving if the ballot initiative to legalize marijuana for those 21 and over passes this November. A blood THC content of 5 nanograms per milliliter or higher will earn a DUI for a driver. But there is currently no standard way to test for THC in the blood.

Colorado is currently at the cutting edge of figuring out how to police high driving. The state also has a 5 ng per ml THC rule, but hasn’t decided how to enforce that law.

Earlier this year, state troopers rolled out a series of demo programs. Five different devices are being used on drivers on a volunteer basis. At the end of two years the state will determine what, if any, of the systems they want to implement.  “I don’t know if we’re going to decide on one, three or none,” said Major Steve Garcia of the State Patrol training branch.

It’s unknown at this point if any of these gizmos can actually determine whether a driver is inebriated or if they just have THC in their blood, which are two very different things.