Driving under the influence of drugs
M Marillier, AG Verstraete - Wiley Interdisciplinary Reviews: Forensic Science
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ABSTRACT: Driving is a very complex task, requiring the cooperation of several different cognitive and psychomotor functions at once. Approximately 2% of the drivers drive under the influence of drugs, sometimes more (20%) and more at specific times (weekend nights). Population surveys show that self‐reported driving after using psychoactive drugs (mostly cannabis) varies between 3.8 and 29.9%. In injured and fatally injured drivers, about 20–40% test positive for drugs. The risk of a crash is almost doubled after cannabis use, increased about seven times after amphetamine use. For the other drugs, the risk falls between these extremes. Amphetamines are estimated to cause half of the fatalities due to driving under the infuence of drugs (DUID). Medicinal drugs, taken according to prescription, only increase crash risk by 20–40%. In France 4% and 3% of the accidents could be prevented if no one drove after taking cannabis and impairing therapeutic drugs, respectively. Three types of DUID legislation exist: “impairment” legislation, “per se” legislation and the “two‐tier” approach that combines both. In impairment legislation, the prosecution must demonstrate that the driver was impaired or “under the influence.” A “per se” law prohibits driving if drugs are present in blood, serum, plasma, or oral fluid (OF) above a certain threshold concentration. OF is commonly used for roadside drug screening of drivers, and increasingly for confirmation as well. Recently developed methods for confirmation analysis, either on blood or on OF, use liquid chromatography (tandem) mass spectrometry (LC–MS[MS]) to test for dozens of drugs on a small sample volume.