Non-compliance with graduated driver licensing (GDL) requirements: changes in GDL-related conviction rates over time...

Self-reports by novice teen drivers in California and elsewhere suggest that many violate graduated driver licensing (GDL) nighttime and passenger restrictions, and to a lesser extent, drive on learner permits without being supervised. Is this corroborated by their traffic conviction records?

We examined historical aggregated conviction rates for GDL-related violations before and after GDL, and Poisson regressions of conviction rates over time among 16-17-year-old California novices.

During the year before they received their provisional licenses, <1% of 16-year-old novices and <2% of 17-year-old novices were convicted of driving unlicensed or unsupervised on their learner permits. Statewide historical conviction rates for these offenses were not higher after GDL was implemented, despite the longer holding period. Convictions for violating GDL nighttime or passenger restrictions were highest almost immediately after provisional licensure, though only about 3% of 16-year-old novices and 2% of 17-year-old novices were ever convicted of violating either restriction.

California 16-17-year-old novice drivers were very rarely convicted of GDL-related violations. The contradictive, large differences between the current findings and self-report surveys are likely due in part to the fact that most self-reports assessed only whether teens had ever violated a GDL-related requirement, which exaggerates prevalence. Our conviction findings are more similar to estimates of non-compliance with GDL-related requirements from naturalistic driving studies that monitor actual driving behavior and take exposure into account, but are lower likely due to issues related to detection, enforcement, and adjudication of violations, as well as limitations of existing naturalistic studies.