Abstract

Reducing marijuana-impaired driving is an important part of any strategy to prevent motor vehicle traffic injuries. In Colorado, the first of eight US states and the District of Columbia to legalise marijuana for recreational use, drivers with positive tests for the presence of marijuana accounted for a larger proportion of fatal MVCs after marijuana commercialisation. The use of blood tests to screen for marijuana intoxication, in Colorado and elsewhere in the USA, poses a number of challenges. Many high-income countries use oral fluid drug testing (OF) to provide roadside evidence of marijuana intoxication. A 2009 Belgium policy implementing OF roadside testing increased true positives and decreased false positives of suspected marijuana-related driving under the influence (DUI) arrests. US policy-makers should consider using roadside OF to increase objectivity and reliability for tests used in marijuana-related DUI arrests.