With marijuana legal for medical or recreational purposes in a number of states, the need has arisen for an easy, reliable test for marijuana impairment. Drug-impaired driving is still illegal in all 50 states, but the current blood and urine tests only indicate whether someone has used the drug in the past month or so. Since marijuana's "high" only lasts for a couple of hours, the tests come out positive in many cases where the driver is long past that "high" stage.
That means that out-of-state drivers who used marijuana legally before ever coming to Texas could test positive for marijuana and be considered impaired even though they are factually not impaired.
Let's be clear; Texas has some of the toughest DWI laws in the country, and that applies to drugged driving, too. Texas goes by a "per se" rule, meaning that drivers who test positive for any amount of an illegal drug in their systems are automatically considered guilty of DWI. The state does not have to prove actual impairment. The state has even made clear that the fact that you were using marijuana legally is not a defense to drugged driving.
But with local jurisdictions including Bexar, Hays, Travis, Williamson and Harris counties decriminalizing marijuana, the issue no longer arises only with out-of-state drivers. Local folks are getting convicted of drugged driving even though they were not actually impaired and even though possession of the drug would only result in a citation or a small fine. That strikes a lot of people as unjust.
What is needed is a test that proves impairment, not just prior use. For technical reasons, that has been very difficult to achieve. Now, however, a California company has announced the development of a "pot breathalyzer" that can detect THC, the psychoactive compound in marijuana, in the breath.
The idea is that THC absorbs pretty quickly into the body, so someone with a detectible level of THC in their breath would likely have used the drug in the past couple of hours -- and is likely, therefore, to be actually impaired.
The breathalyzer-like device took five years to develop and is just in the testing stage. Several law enforcement agencies will be field testing it this fall.
Will the "pot breathalyzer" provide admissible evidence of a driver's marijuana impairment? It's too early to tell. If it does, it could be a game changer because it would allow police and prosecutors to weed out those who merely had smoked in the last month from those who actually hit the road while high.