Sobriety Cases
Objective
To assess how two types of drinking-driving laws—permitting sobriety checkpoints and prohibiting open containers of alcohol in motor vehicles—are associated with drinking-driving, and how enforcement efforts may affect these associations.
Methods
We obtained 2010 data on state-level drinking-driving laws and individual-level self-reported drinking-driving from archival sources (Alcohol Policy Information System, National Highway Traffic Safety Administration, and Behavioral Risk Factor Surveillance System). We measured enforcement of the laws via a 2009 survey of state patrol agencies. We computed multi-level regression models (separate models for each type of law) that first examined how having the state law predicted drinking-driving, controlling for various state- and individual-level covariates; we then added the corresponding enforcement measure as another potential predictor.
Results
We found that states with a sobriety checkpoint law, compared to those without a law, had 18.2% lower drinking-driving; states that conducted sobriety checks at least monthly (vs. not conducting checks) had 40.6% lower drinking-driving (the state law variable was not significant when enforcement was added). We found no significant association between having an open container law and drinking-driving, but states that conducted open container enforcement, regardless of having a law, had 17.6% less drinking-driving.
METHODS
We obtained data at the state level (sobriety checkpoint and open container laws) as well as at the individual level (drinking-driving) for the 50 U.S. states. We also measured state-level enforcement practices via a survey of state-level law enforcement agencies. The study was approved by the University of Minnesota’s Institutional Review Board.