Law enforcement officers already use breathalyzers as a preliminary test for blood-alcohol content. Soon, they might have a similar test to detect marijuana usage.

Researchers at Washington State University are developing a breathalyzer for pot.

According to FOX 8, the device “would be used by police in states that have already legalized the drug.”

Even in the states where the recreational use of marijuana is legal (Washington, Alaska, Colorado and Oregon), drivers can be charged with driving under the influence if they test positive for five or more nanograms of a chemical called tetrahydrocannabinol (or THC) per milliliter of blood, according to FOX 8.

Law enforcement officers currently lack a portable tool to test for pot use and are dependent on a blood test to determine if a driver is above the limit.

According to the News Tribune, “Stoned drivers have become an increasing concern since Washington voters legalized recreational use of marijuana in 2012. A quarter of blood samples taken from drivers in 2013, the first full year the initiative was in effect, came back positive for pot.”

WSU chemistry professor Herbert Hill told the Tribune that he and doctoral student Jessica Tufariello are working on a portable device that would make results “immediately available” to police.

“[An officer] would have a higher level of confidence in making an arrest,” said Hill.

Cully Stimson, manager of The Heritage Foundation’s National Security Law Program, said that “drivers under the influence of alcohol or drugs are a serious problem in the United States:”

For decades police have used hand-held passive alcohol screening devices in the field to confirm the presence of alcohol from suspects drunk drivers. Those PAS alcohol devices are accurate and highly effective.

If inventors and scientists are able to develop a similar device to test for a certain level of THC (the active ingredient in marijuana) that is accepted by the scientific community as reliable, that would be a welcome sign.

According to FOX 8, “researchers will begin testing the new Breathalyzer in 2015.”