Marijuana use has increased in Illinois now that many states have legalized marijuana for medical purposes. However, use of marijuana can slow reaction time and cause impaired driving. Researchers are developing a saliva test that could potentially change marijuana DUI investigations.

Currently, suspected impaired drivers may be asked to take a breath test for the presence of alcohol in the driver’s bloodstream. There is no breath test available to detect recent marijuana use. The only options available in DUI drug investigations to test for marijuana are blood and urine tests.

Scientists are reporting that they are close to developing a saliva test that can detect cannabis use. They have presented their findings online through the American Chemical Society SciMeetings.

Researchers have correlated blood alcohol concentration levels above certain amounts with impairment. The compound in marijuana that causes its intoxicating effects, tetrahydrocannabinol or THC, has not been studied as extensively, but researchers suggest that any amount above 1 to 15 nanograms of THC per milliliter of blood is considered a level of impairment.

A saliva test developed at the University of Texas uses sensors coated with an antibody that binds with THC to separate the THC molecules from other substances in saliva samples. An electric current is passed through the sensors to detect the amount of THC concentration in the sample.

Drivers who have been charged with a DUI may benefit from speaking to an attorney about their possible defenses. If the investigation involved a test or method that is not widely accepted or studied in DUI investigations, it may be possible for an attorney to request that the evidence be excluded from use at trial. DUI investigations where drugs were suspected may be easier to challenge in some cases because impairment by drugs has not been clinically studied as extensively as the effects of alcohol.