Breath test technology and reliability is an important aspect of the criminal justice process for anyone accused of impaired driving. At Washington State University, research is currently underway to develop a marijuana breath test. Researchers are working to develop a breath test for marijuana that is similar to blood alcohol tests currently used by law enforcement authorities for alcohol. A chemistry professor at the university noted that certain current technologies used for drug detection purposes can be "repurposed" to test breath for THC. THC is the psychoactive component of marijuana. In Washington state, five nanograms of active THC per milliliter of blood is the legal limit for drivers.
According to researchers, the marijuana breath test that is being developed is not likely to provide the exact level of THC present in the driver's body; rather, the breath test that is being developed will inform officers that some level of active THC is present in the driver's body. Researchers believe this will help law enforcement authorities determine if a driver suspected of impaired driving should be arrested and will minimize so-called "false positives." Follow up tests would have to be conducted by police to be used as evidence in a court proceeding. Tests presumably include blood or urine tests such as those currently used to measure alcohol. The device is currently in the development phase and testing is expected to begin next year, first on human breath and then in the field.