Health Insurance Mandates and Traffic Fatalities

We investigate whether state health insurance parity laws adopted in the 1990s and 2000s for substance use disorder (SUD) treatment reduce traffic fatalities in the United States. Impaired driving is a major contributing factor to US traffic fatalities. State health insurance parity laws compel private insurers to cover SUD treatment more generously—on par with physical health services. We employ 21 years of administrative data from the Fatality Analysis Reporting System. We estimate both two-way fixed-effects regressions and an interaction-weighted estimator that is robust to potential bias attributable to heterogenous and dynamic treatment effects with staggered policy adoption. Our findings indicate that state parity law passage reduces overall traffic fatality rates by 2.8 percent, with larger effects for fatalities that involve alcohol. These findings suggest that state regulations requiring private insurers to equitably cover SUD treatment can improve traffic safety.