Laboratory Validation Study of Drug Evaluation and Classification Program: Ethanol, Cocaine, and Marijuana

The Drug Evaluation and Classification (DEC) program is used by police agencies to determine if individuals are behaviorally impaired because of drug use, and, if impaired, to determine the class of drug(s) causing the impairment. Although widely used, the validity of the DEC evaluation has not been rigorously tested. The primary goal of this study was to determine the validity of the variables of the DEC evaluation in predicting whether research volunteers had been administered ethanol, cocaine, or marijuana; a secondary goal was to determine the accuracy of trained police officers (Drug Recognition Examiner, DRE) in detecting whether subjects had been dosed with ethanol, cocaine, or marijuana. Community volunteers (n = 18) with histories of drug use received ethanol (0, 0.28, 0.52 g/kg), cocaine (4, 48, 96 mg/70 kg), and marijuana (0, 1.75, 3.55% THC) in a double-blind, randomized, within-subjects design. A single drug dose or placebo was administered during each of nine experimental sessions, and blood samples were obtained before and periodically after dosing. With the exception of marijuana, plasma drug concentration was at or near the observed maximum during the DEC evaluation. The ability of the DEC evaluation to predict the intake of ethanol, cocaine, or marijuana was optimal when using 17-28 variables from the evaluation. When DREs concluded impairment was due to drugs other than ethanol, their opinions were consistent with toxicology in 44% of cases. These findings suggest that the DEC evaluation can be used to predict accurately acute administration of ethanol, cocaine, or marijuana, and that predictions of drug use may be improved if DREs focused on a subset of variables.