Police in Virginia have several ways to test alcohol impairment in drivers, but they do not have the same types of tests for marijuana impairment. So far, there are no universally accepted roadside tests that police can use to test drivers’ marijuana intoxication levels. However, some researchers from the University of Texas are working on a saliva test that they believe could detect THC levels in less than five minutes.

Marijuana is still illegal in Texas, so UT researchers have not been able to study saliva samples from people who have actually smoked or consumed the drug. Instead, researchers are using saliva samples that have been spiked with THC for the purposes of testing. The test has been shown to detect both low and high concentrations of THC in the samples.

Although they haven’t conducted tests on any real marijuana consumers yet, UT researchers have already created a version of the saliva test that may be applicable in roadside stops. The test is about the size of a glucose monitor, and researchers think it could have other applications outside law enforcement. Researchers and law enforcement in other states where marijuana is legal have expressed interest in collaborating with UT researchers.

Even tests that have been used by law enforcement for years are imperfect and sometimes display false readings. If a driver is accused of marijuana intoxication, a questionable test and a police officer’s observation and opinion may be the only evidence against them. A criminal defense attorney may be able to represent an individual who was accused of impaired driving and argue that there is no solid evidence of intoxication.