Motor Vehicle Injury Alcohol-Impaired Driving: Lower BAC Laws for Young or Inexperienced Drivers
Findings and Recommendations
The Community Preventive Services Task Force (CPSTF) recommends laws that establish a lower illegal blood alcohol concentration (BAC) for young or inexperienced drivers than for older or more experienced drivers based on evidence they reduce alcohol-related motor vehicle crashes.
The full CPSTF Finding and Rationale Statement and supporting documents for Reducing Alcohol-Impaired Driving: Lower Blood Alcohol Concentration (BAC) Laws for Young or Inexperienced Drivers are available in The Community Guide Collection on CDC Stacks.
Intervention
In the United States, lower blood alcohol concentration (BAC) laws apply to all drivers under the age of 21. Between states, the illegal BAC ranges from any detectable BAC to 0.02%.
In other countries, lower BAC laws apply to either newly licensed drivers or newly licensed drivers under a specified age.
About The Systematic Review
The CPSTF finding is based on evidence from a systematic review of six studies (search period through June 2000).
Study Characteristics
- Included studies evaluated the number of motor vehicle crashes from one to 15 years after enactment of lower BAC laws (median 22 months) using the information in police reports.
- Studies reported fatal crashes (3 studies), fatal and nonfatal injury crashes (2 studies), and crashes in which the investigating police officers believed the driver had been drinking alcohol (1 study).
- Studies were conducted in the United States (4 studies, two of which evaluated laws in multiple states) and Australia (2 studies). States studied were geographically diverse, with both urban and rural populations represented.
Summary of Results
The systematic review included six studies.
- Fatal crashes decreased by 24%, 17%, and 9% (3 studies).
- Fatal and nonfatal injury crashes decreased by 17% and 4% (2 studies).
- Crashes in which the investigating police officer believed that the driver had been drinking alcohol decreased by 11% (1 study).
Summary of Economic Evidence
- The one study that qualified for the economic review estimated a benefit-to-cost ratio for lower BAC laws of $11 per dollar invested when violators received a six-month license suspension.
- The study, a cost benefit analysis, applied previously published crash costs and used effectiveness data from other previously published studies to illustrate how these costs could be applied to lower BAC laws in the U.S.
- The benefits from a reduction in alcohol-related crashes were estimated using the assumption that lower BAC laws reduce young drivers’ alcohol-related crashes by 20%.
Applicability
These results should be applicable to all young and inexperienced drivers covered by lower BAC laws (in the United States, those under 21 years of age).
Evidence Gaps
- How do variations in enforcement levels influence the effectiveness of laws to reduce alcohol-impaired driving?
- What are the independent effects of publicity on the effectiveness of laws to reduce alcohol-impaired driving?
- Does public compliance with new laws change in a predictable manner over time?
- How do interventions to reduce alcohol-impaired driving interact with each other (e.g., 0.08% BAC laws and administrative license revocation)?
- What effects do these interventions have on long-term changes in social norms about drinking and driving?
- Are interventions equally effective in rural and urban settings?
- Are interventions equally effective when applied to populations with different baseline levels of alcohol-impaired driving?
- What proportion of youths charged with violating zero tolerance laws had BAC levels elevated enough to warrant a more serious drinking-driving offense?
- Do interventions to reduce alcohol-impaired driving reduce other forms of alcohol-related injury?
- What are the cost-benefit, cost utility, and cost-effectiveness of interventions?
- What role can community coalitions play in removing barriers to implementing interventions designed to prevent alcohol-impaired driving?
Implementation Considerations and Resources
The CPSTF recommendation and evidence from this review may be used to inform decisions about maintaining lower BAC laws for young or inexperienced drivers. Following are considerations drawn from studies included in the evidence review, the broader literature, and expert opinion.
- Engage partners throughout the process. Building support from the ground up can help secure policies that reinforce healthy behaviors in the community.
- Demonstrate why the policy is important. Use CPSTF findings and recent surveillance data to show partners how policies have been effective.
- Educate stakeholders. Keep the media, community influencers, and policymakers informed about lower BAC laws to help communicate messages that are accurate and timely.
- Keep messages brief and to the point. Use graphics, figures, or infographics to clearly demonstrate how the intervention can improve health outcomes.
- Extend your communication reach by working through partners who have the most credibility with key audiences.
- Pay attention to sustainability. Continue to conduct surveillance related to alcohol-impaired driving and disseminate findings.
- Lower BAC laws may be useful in populations other than young drivers. For example, CDC recommends that states consider enacting lower BAC laws for all drivers who transport children.
- Lower BAC laws can result in underage drinking drivers with high BACs receiving only zero tolerance citations rather than being arrested for alcohol-impaired driving (as would drinking drivers 21 years and older).
- Following are potential barriers to full enforcement of lower BAC laws:
- Because young people are less likely than adults to drink in bars, police patrols that target bar neighborhoods are likely to miss underage drinking drivers.
- Officers may have difficulty identifying underage drinking drivers with low BACs because they may not show obvious signs of impairment.
- Because of ambiguities, some state laws prohibit police officers from testing the BAC of an underage driver unless there is probable cause to believe that the driver’s BAC is above the legal limit for adults.
Crosswalks
Healthy People 2030 includes the following objectives related to this CPSTF recommendation.