A Washington State University professor is currently developing the first portable breathalyzer that tests for marijuana substance consumed by a driver. Washington law enforcement agencies are particularly enthusiastic about the test, as more and more drivers are operating while under the influence of marijuana in one of only two states who have legalized marijuana.

Currently, law enforcement can only test for marijuana consumption through blood tests at a lab. These tests are time consuming, complicated, and expensive. The new marijuana breath test is designed to detect a primary chemical ingredient – THC – in the driver’s breath immediately after the driver is pulled over. A portable breath test for marijuana will enable officers to more accurately identify drivers who operate while under the influence of marijuana, by allowing them to rely on the breathalyzer’s measurements rather the officers’ own observations.

Like most alcohol breathalyzers, marijuana breathalyzer devices will likely be susceptible to error. There are currently several ways for an experienced criminal defense attorney to challenge the results of an alcohol breathalyzer – from the manner in which the test was administered to the significance of the chemical ingredients that a breathalyzer actually detects and measures. These challenges could also be expected in a prosecution relying on a marijuana breathalyzer test result. But still, the invention of a marijuana breathalyzer is likely to lead to substantially tougher prosecution of this type of offense – not only in Colorado and Washington where driving while under the influence of marijuana is explicitly a crime, but in other states as well. USA Today along with several media outlets reported on this story.

Under existing Massachusetts law, for example, a person could be charged with operating under the influence of drugs, which is distinct from the charge of operating with a BAC level greater than .08 percent (the “per se” charge) and even the charge of operating under the influence of alcohol. Prosecutors could (and frequently do) charge drivers with a combination of these offenses, since the OUI charges only address impaired driving due to consumption of a substance, while the per se offense requires only a showing that a driver’s blood-alcohol-content level was greater than the statutory limit. Equipped with these new marijuana breathalyzer devices, Massachusetts law enforcement is likely to increase OUI Drugs arrests.

This technology would be the newest tool in the state’s large arsenal used for regulating and prosecuting individuals for substance use. It is expected to be completed by the end of this year, and will be tested throughout 2015.