Page last updated: March 27, 2017

Ignition Interlock Laws: Effects on fatal motor vehicle crashes, 1982–2013

In the US, alcohol-involved motor vehicle lead to more than 10,000 fatalities in 2013, making them a major cause of preventable mortality. Ignition interlocks are a promising way to prevent drunk driving.

A study assessed the effects of laws requiring ignition interlocks for some or all drunk driving offenders on alcohol-involved fatal crashes. A multilevel modeling approach assessed the effects of state interlock laws on alcohol-involved fatal crashes in the US from 1982 to 2013. Monthly data on alcohol-involved crashes in each of the 50 states was collected in 2014 from the National Highway Traffic Safety Administration Fatality Analysis Reporting System. Based on an analysis conducted in 2015, the study found that State laws requiring interlocks for all drunk driving offenders were associated with a 7% decrease in the rate of BAC >0.08 fatal crashes and an 8% decrease in the rate of BAC ≥0.15 fatal crashes, translating into an estimated 1,250 prevented BAC >0.08 fatal crashes.

The findings show that laws requiring interlocks for segments of high-risk drunk driving offenders, such as repeat offenders, may reduce alcohol-involved fatal crashes after 2 years of implementation. Ignition interlock laws reduce alcohol-involved fatal crashes, so increasing the spread of interlock laws that are mandatory for all offenders would have significant public health benefit, they conclude.

Source: Ignition Interlock Laws: Effects on Fatal Motor Vehicle Crashes, 1982–2013, Gregory Tung, Juliana Shulman-Laniel, Rose Hardy, , Lainie Rutkow, Shannon Frattaroli, Jon S. Vernick. American Journal of Preventative Medicine.

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