Drinking drivers missed at sobriety checkpoints

Sobriety checkpoints are an effective deterrent to alcohol-impaired driving although a substantial proportion of drinking drivers who pass through checkpoints are missed. The present study was designed to determine the extent to which police officers correctly identify individuals with blood alcohol concentrations (BACs) at or above 0.05% at checkpoints, and if there are characteristics of drivers, vehicles or checkpoints that are associated with decreased chances of detection.

To determine which drivers are likely to be missed, drivers not detained by police for additional sobriety evaluation were interviewed and voluntary breath samples were provided at 156 sobriety checkpoints in North Carolina.

More than 50% of the drivers with BACs in excess of 0.08% and almost 90% of drivers with BACs in excess of 0.05% were not detained by officers. For drivers with BACs of 0.05% or higher, women and those 35 or younger were more likely to be missed than were men and older drivers. Drivers without passengers were more likely to be missed than those with passengers. Drivers were also more likely to be missed during weekend checkpoints. Similar results were found for drivers with BACs at or above 0.08%.

Alerting police officers to characteristics of drinking drivers more likely to be missed may improve detection rates. In addition, passive alcohol sensors could improve the effectiveness and efficiency of sobriety checkpoints in detecting drinking drivers.