A report released in April, 2017 from the Governors Highway Safety Association (GHSA) in response to legislatures, law enforcement, and highway safety offices being urged to about drug-impaired driving. It includes information obtained by GHSA from a survey of state highway safety offices. According to the report, drug-impaired driving is more complex than alcohol-impaired driving for many reasons:
- Hundreds of different drugs can impair drivers. Some drugs that can impair driving are illegal to use, some are legal to use under certain conditions, and some are freely available over-the-counter.
- For many drugs, the relation between a drug’s presence in the body, its effect on driving, and its effects on crash risk are complex, not understood well, and vary from driver to driver. Additionally, some drugs – especially cannabis – attach to the fatty tissues of the body and therefore cannot be measured as blood concentration levels as is done with alcohol.
- Data on drug presence in crash-involved drivers are incomplete in most jurisdictions, inconsistent from state to state, and sometimes inconsistent across jurisdictions within states. Additionally, laws regarding driving while under the influence of drugs (DUID) vary across the states.
- It is more difficult for law enforcement to detect drug impairment at the roadside than alcohol impairment. There are no BAC charts or understanding the stages for becoming impaired while using some drugs such as cannabis as there are for alcohol.
- Data on drug presence in crash-involved drivers are incomplete in most jurisdictions, inconsistent from state to state, and sometimes inconsistent across jurisdictions within states. While laws regarding driving while under the influence of drugs (DUID) vary across the states, it is still more difficult to prosecute and convict a driver for DUID than for alcohol-impaired driving (DUI/DWI/OWI).
Drug-impaired driving is an increasingly critical issue for states and state highway safety offices. As of April 2017, marijuana may be used for medical purposes in 29 states and the District of Columbia, although these states are still struggling with legislating its use, cultivation, and sale. While these states have decriminalized possession of small amounts of marijuana, it is still a federal crime and cannot be transported across state lines. Furthermore, in every state it is still a crime to drive impaired under the influence of drugs or alcohol, including marijuana. In 2015, the most recent year for which data are available, the National Highway and Traffic Safety Administration’s Fatality Analysis Reporting System (FARS) reported that drugs were present in 43% of the fatally-injured drivers with a known test result, more frequently than alcohol was present. NHTSA’s 2013–2014 roadside survey found drugs in 22% of all drivers both on weekend nights and on weekday days. In particular, marijuana use was cited as increasing.
Congress identified drug-impaired driving as a priority in the Fixing America’s Surface Transportation (FAST) Act of 2015. This multi-year highway bill directed NHTSA to develop education campaigns to increase public awareness about the dangers associated with drugged driving. The Act also required the Department of Transportation to study the relationship between marijuana use and driving impairment and to identify effective methods to detect marijuana-impaired drivers.
Legislatures, law enforcement, and highway safety offices in many states are urged to “do something” about drug-impaired driving, but what to do is far from clear. While the report does not attempt to be a complete review of the extensive information available on drugs and driving, it does provide references to research and position papers, especially papers that summarize the research on drugs and driving that have appeared in the last 20 years.
Watch the CNN video, “Your Brain on Weed” for an insight on marijuana and TCH, the chemical that gets you high.