Select Page

With legal marijuana sweeping the nation, law enforcement is taking a wider view of driving under the influence. If you’re caught driving with even a trace of marijuana in your system in Tennessee, you can face severe penalties, as we’ve discussed before.

Getting caught possessing marijuana is one thing, but how do law enforcement know if there’s marijuana in your system when they pull you over? And does that necessarily mean you’re still under the influence?

The marijuana breathalyzer has become a sort of holy grail for answering these kinds of questions, but it looks like it may be years before there’s a reliable roadside test available, according to Scientific American.

One challenge with existing tests that is they often still detect the active ingredient tetrahydrocannabinol (THC) even weeks after a person smoked or consumed cannabis. There’s plenty of motivation to develop a more reliable test, and a number of companies claim to have created portable marijuana tests for law enforcement to use.

One device from a California company, Hound Labs, may be available to law enforcement by the end of the year. But it will take quite a bit of time for researchers to determine whether these breathalyzer-like devices accurately measure the amount of marijuana in a person’s system – and how this relates to a driver’s actual impairment.

In the meantime, law enforcement may rely on a combination of field sobriety tests and blood or urine tests for investigating whether a driver is impaired.

As roadside tests become more common, however, there are likely to be some false positives. If you believe you’ve been unfairly charged with driving under the influence of marijuana, you may want to talk to a criminal defense attorney about whether the test used was reliable.