A drug recognition expert (DRE), sometimes referred to as a drug recognition evaluator, is an individual who has successfully completed all phases of the Drug Evaluation and Classification Program's (DECP) training requirements for certification as established by the International Association of Chiefs of Police (IACP) and the National Highway Traffic Safety Administration (NHTSA). A DRE is skilled in detecting and identifying persons under the influence of drugs and in identifying the category or categories of drugs causing the impairment.