Dialing While Fishtailing: How Mobile Phones, Hands-Free Laws, and Driving Conditions Interact to Affect Traffic Fatalities

Most rich countries in the world and four US states require drivers talking on mobile phones to use hands-free devices. However, previous research has failed to arrive at a consensus on the effect of mobile phones on traffic accidents yet has concluded that the effect of hands-free and hand-held phones on accidents is similar. This paper uses state-level data from 1997-2005 on mobile phone ownership, traffic fatalities, and hands-free laws and finds that (1) mobile phones contribute to traffic fatalities and (2) hands-free laws appear to reduce fatalities. Specifically, mobile phone ownership results in a large and statistically significant increase in traffic fatalities in bad weather or wet road conditions, with no effect in good weather or dry road conditions. Laws requiring drivers to use hands-free technologies while talking reduce traffic fatalities in adverse conditions, and the effect grows stronger and becomes statistically significant the longer the law is in effect, although these longer-term effects are based solely on New York, which in 2001 became the first state to have a hands-free law. The analysis relies on microdata from the Fatality Analysis Reporting System to estimate effects for traffic fatalities in different conditions and to isolate fatalities unlikely to be affected by confounding changes in alcohol policies or graduated licensing laws.