Monday, October 20, 2008

Mandatory seat belt laws

A recent paper in the May 2008 edition of the Journal of Health Economics by Carpentera and Stehr finds that mandatory seat belt laws save lives.

“…we find consistent evidence that state mandatory seatbelt laws – particularly those permitting primary enforcement – significantly increased seatbelt use among high school age youths by 45–80%, primarily at the extensive margin. Unlike previous research for adults, however, we find evidence against the selective recruitment hypothesis: seatbelt laws had consistently larger effects on those most likely to be involved in traffic accidents (drinkers, alcohol-involved drivers). We also find that mandatory seatbelt laws significantly reduced traffic fatalities and serious injuries resulting from fatal crashes by 8 and 9%, respectively. Our results suggest that if all states had primary enforcement seatbelt laws then regular youth seatbelt use would be nearly universal and youth fatalities would fall by about 120 per year.”

So should we implement mandatory seat belt laws? From the evidence in their paper, Carpentera and Stehr believe so. However, is this issue truly so clear cut?

One question is whether or not mandatory seat belt laws really caused increased seat belt use. Did the seat belt laws cause increased seat belt use or did increased seat belt use lead to the increased popularity and passage of a law?

This paper is important in that it quantifies the benefits of the mandatory seat belt laws, but does not quantify the costs. What is the cost of enforcement in terms of 1) time law enforcement must dedicate to seat belt policing instead of “real” police work? and 2) the cost to the justice system and work absences due to the adjudication or appeals process for seat belt violation, and 3) the violation of a person’s individual freedom to choose to not wear a seatbelt. In this case, there is no externality to not wearing a seat belt; the person harmed from not wearing a seat belt is that person themselves. A libertarian would be strictly against a mandatory seat belt law. Nevertheless, a compelling argument can be made that minors do not use an optimal decision-making process when deciding whether or not to wear a seat belt.

Do I support a mandatory seat belt law? No.

I believe that parents should help to convince their child to use seat belts and that it is possible that schools should educate children on the benefits of using a seat belt. However, using police resources to fine individuals who do not wear seat belts seems to be a waste of resources. If mandatory seat belt laws are not enforced, then this would free up police resources, but also would weaken the impact of mandatory seat belt laws.

Seat belt save lives. But I think parents and schools–not the government–are the best institutions to spread this message.

* Christopher S. Carpentera and Mark Stehr (2008) “The effects of mandatory seatbelt laws on seatbelt use, motor vehicle fatalities, and crash-related injuries among youths“, Journal of Health Economics, Volume 27, Issue 3, Pages 642-662.


Irwin said...

The author confuses the issues of mandatory seat belt laws and enforcement. All states in the US except New Hampshire have a mandatory seat belt. Twenty six states and DC have a primary enforcement law - allowing police to stop and fine people for not wearing a seat belt. Twenty four states still have secondary enforcement laws which means police cannot stop and fine someone only for lack of seat belt use.

As pointed out by the authors of the article in the Journal of Health Economics and an abundance of existing evidence in the scientific literature, seat belts save lives. Primary laws result in increased seat belt use and decreased death and injury due to moter vehicle crashes.

The author's arguments about the cost of enforcement are inaccurate. Point 1) enforcing seat belt laws is not "real" police work - enforcing all laws is real police work. Most police chiefs and officers tell us that enforcing traffic laws (inlcuding seat belt enforcement) leads to capture of wanted felons, DUIs and other various assorted criminals. The bad guys are not on horses, they are driving through our towns and cities.

3)Lack of seat belt use only harms the individual. That idea couldn't be more inaccurate. When someone is killed or seriously injured in a car crash, the ambulance and EMTs at the scene are likely to be public employees who will likely take the victim or victims to a public hospital. There's ample documentation that injuries to someone who was not buckled are more expensive to treat in the emergency room and afterwards than injuries to someone who was buckled. Further, if someone is seriously injured and disabled, they will likely go through their insurance quickly and end up on medicaid (public support) for many years.

After all the years of financial investment by the State in its citizens (schools, education, roads, etc.) it is foolish of the state to allow citizens to endanger themselves and others in a car crash.

We are not just talking about spreading the message about seat belt use. As we already stated above, it's the law in 49 states and DC. We are talking about enforcing the law.

marzuki said...

Thanks for the insight Irwin! I liked point no. 1.

Me and some friends were discussing about it just this morning!