DUID prevalence in Colorado's DUI citations

• At least 30% of Colorado's DUIs were drug related in 2013.
• Polydrug use was the most common cause of Colorado's DUID citations in 2013.
• Marijuana was the 5th most common cause of Colorado's DUI citations in 2013.
• Warrants can render blood test results meaningless in cases of marijuana-impairment.
• DUI-alcohol laws are inadequate to deal with drugged driving.

IntroductionThere are limited studies that measure the prevalence of driving under the influence of drugs (DUID) based upon impairment measures because most prevalence studies are based on drug tests. The aim of this study was to provide the first estimate of DUID prevalence in Colorado using data collected by Colorado law enforcement officers in vehicular homicide (VH) and vehicular assault (VA) cases, and reported in court records.MethodsThe four research questions of this study were answered by completing independent t-tests or Mann–Whitney U tests, Pearson chi-square analyses or Fisher's exact tests, and Kruskal–Wallis tests.ResultsSeventy percent (119 out of 170) of the cases involved alcohol only and 30% (51 out of 170) involved drugs. Of the latter cases, 32 cases involved a combination of alcohol and drugs and 19 cases identified drugs only, with no alcohol. Marijuana was the most commonly cited drug (23 cases); however, it was the sole impairing substance identified in only three cases.ConclusionPolydrug use was very common among DUID cases, which makes it difficult to identify which drug or drugs caused the impairment responsible for the Driving Under the Influence citation. This study revealed tha (a) drugged driving is a frequent cause of DUI citations in cases charged with VH or VA; (b) that polydrug use, rather than marijuana, is the most common cause of drugged driving in Colorado; and (c) that current warrant procedures render blood test results meaningless in cases of marijuana-impairment.Practical applicationStates should collect and analyze DUID data to ensure legislators focus on the right DUID problems to improve biological testing for drugs, adopt more appropriate roadside testing, and enact stronger DUID laws to protect the public.