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What GAO Found

Various state and national-level data sources—including surveys, arrest data, drug-testing results, and crash data—provide limited information on the extent of drugged and drug-impaired driving in the United States. For example, based on preliminary results from a representative sample of weekend-nighttime and Friday daytime drivers, the National Highway Traffic Safety Administration's (NHTSA) 2013-2014 National Roadside Survey of Alcohol and Drug Use by Drivers ( NRS ) estimated that 20 percent of drivers would have tested positive for at least one drug, with marijuana being the most common drug. However, the survey does not capture the extent to which drivers were impaired by drugs. Arrest data and drug-testing results provide some information on drug-impaired driving, but these data are limited. For example, data for drug impairment may not be separated from that for alcohol impairment and drug testing is not standardized. According to NHTSA officials, currently available data on drug involvement in crashes are generally unreliable due to variances in reporting and testing.

The lack of a clear link between impairment and drug concentrations in the body makes it difficult to define drug impairment, which, in turn, exacerbates challenges related to enforcement and public awareness. Compared to alcohol, defining and identifying impairment due to drugs is more complicated due to the large number of available drugs and their unpredictable effects. For example, the NRS includes tests for 75 illegal prescriptions, and over-the-counter (OTC) drugs identified as potentially impairing. Additionally, law enforcement processes for obtaining samples for drug testing can be time consuming and result in a loss of evidence. For example, there is no validated device for roadside drug testing, and obtaining a search warrant to collect a blood sample to confirm the presence of drugs in a driver's system could take several hours, during which time the concentration of the drug in the driver's system could dissipate. Further, state officials identified limited public awareness about the dangers of drugged driving as a challenge. As a result, members of the public may drive while impaired without knowing the risks, potentially leading to collisions, injuries, and fatalities.

Federal and state agencies—including NHTSA, the White House Office of National Drug Control Policy (ONDCP), and the Department of Health and Human Services (HHS)—are taking actions to address drug-impaired driving, including improvements in the areas of research and data, education for police officers, evidence gathering, and legal changes. For example, NHTSA is currently conducting research to assess the crash risk associated with drug use (including illegal, prescription, and OTC drugs) by collecting samples from more than 10,000 drivers. However, public awareness of the dangers of drug-impaired driving is an area in which state officials told us that NHTSA could do more to support their efforts. As part of its mission to support state safety efforts, NHTSA has provided media and other materials to states for impaired-driving awareness programs, but these materials are focused on alcohol-impaired driving. While NHTSA plans to improve public awareness through initiatives to conduct surveys on drug-impaired-driving behaviors and attitudes as well as training for medical professionals, these plans could take several years to implement. Additional efforts, such as general messaging reminding the public about the impairing effects of drugs, could help improve public awareness in the near term.

The issue of alcohol-impaired driving has received broad attention over the years, but drug-impaired driving also contributes to fatalities and injuries from traffic crashes. However, knowledge about the drug-impaired- driving problem is less advanced than for alcohol-impaired driving.

Through Senate Report No. 113-45 (2013), Congress required GAO to report on the strategies NHTSA, ONDCP, and states have taken to address drug-impaired driving and challenges they face in detecting and reducing such driving. This report discusses (1) what is known about the extent of drug-impaired driving in the United States; (2) challenges that exist for federal, state, and local agencies in addressing drug-impaired driving; and (3) actions federal and state agencies have taken to address drug-impaired driving and what gaps exist in the federal response. GAO reviewed literature to identify sources of data on drug-impaired driving; reviewed documentation and interviewed officials from NHTSA, ONDCP, and HHS; and interviewed officials from relevant advocacy and professional organizations and seven selected states. States were selected based on: legal status of marijuana, proximity to states with legalized marijuana, and drugged-driving laws.

GAO recommends that NHTSA take additional actions to support states in emphasizing to the public the dangers of drug-impaired driving. DOT agreed with GAO's recommendation.

For more information, contact Susan Fleming, at (202) 512-2834 or flemings@gao.gov.