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MU Professor Recommends Changing Drivers' Perceptions of Law Enforcement to Deter Drinking and Driving

December 23, 2008

COLUMBIA, Mo. - Recent data from the National Highway Traffic Safety Administration (NHTSA) revealed that an estimated 2 million drunk drivers with three or more convictions will be on the roads this holiday season. In 2007, approximately 1,500 people nationwide were killed in crashes that involved a drunk driver from Thanksgiving through New Year's Day. Researchers from the University of Missouri and the University of Georgia found that the most important deterrence factors for high-risk drivers are their perceptions of the likelihood of being stopped or arrested and their support for deterrence laws.

All U.S. states have laws designed to deter impaired driving, but there is little evidence on what works to deter drivers who have a high risk of drinking and driving. The researchers found that the existence of laws, such as the .08 blood alcohol content and open container restrictions, affect only those less likely to drink and drive, and the actual number of impaired driving arrests in a state has no significant effect on drivers' likelihood of drinking and driving.

"Essentially, law enforcement needs to focus on perceptions; it is important that drivers perceive that they will be caught if they drive impaired," said Lilliard Richardson, professor in the MU Truman School of Public Affairs. "We found that high-risk drivers are less likely to drink and drive if they perceive they are likely to be stopped or arrested by police. However, the mere existence of laws designed to discourage people from drinking and driving does not impact high-risk drivers. The results provide support for the value of high-visibility enforcement campaigns. Public safety education and media efforts are important components of the overall strategy for reducing impaired driving."

Previous studies have found conflicting evidence on the effectiveness of strategies that deter drinking and driving behavior. Richardson and Anthony Bertelli, associate professor of public administration and policy at the University of Georgia, assessed drinking and driving laws to determine if their enforcement influenced individuals' likelihood of drinking and driving and if the impact was direct or through perception. The researchers measured the propensity to drink and drive of 6,000 respondents interviewed as part of NHTSA's 2001 National Survey of Drinking and Driving Attitudes and Behavior. The measurements were used to assess the impact of perceptions of enforcement, actual enforcement levels and deterrence laws.

In the study, the majority of participants were less likely to drink and drive if they perceived a probability of being stopped or arrested by law enforcement. Individuals of different risk levels who agreed with the goals of deterrence laws, including sobriety checkpoints and open container laws, also were less likely to drive intoxicated.

"No single effort to reduce drinking and driving will be the most effective with all citizens, but state efforts designed to change enforcement perceptions and gain support of policy goals are most likely to influence a broad array of drivers," Richardson said.

The study, "The Behavioral Impact of Drinking and Driving Laws," was published in the December 2008 issue of the Policy Studies Journal.

University of Missouri