Wednesday, January 20, 2010

The Effects of Mandatory Helmet Laws on Cycling


In yesterday's New York Times, Stephen Dubner of Freakonomics fame, wrote (here) about this new study, which finds that mandatory helmet laws, currently in effect in 21 states, do three things, two of which are intended and one of which is unintended. The two intended effects are to increase the rate of helmet use and reduce the rate of cycling fatalities. So far, so good. However, mandatory cycling laws also tend to discourage cycling among youth who (a) cannot afford helmets or (b) consider helmets "uncool."

Two things strike me about both the study and Dubner's assessment of it. First, why should anyone be surprised that mandatory helmet laws would affect the rate of cycling. It is well understood in the Law and Economics literature that strict liability rules affect both the level of care and activity levels. So, for example, road builders who use dynamite for blasting are strictly liable for any damage they cause to neighboring properties. This leads them to be very careful in using dynamite and to use bulldozers instead of dynamite whenever feasible. A mandatory helmet law is like a strict liability rule in that riding without one imposes automatic, strict liability. Therefore, we should not be particularly surprised that it has the effects of a strict liability rule in both increasing the use of helmets and discouraging some amount of cycling.

Second, if cycling helmets are so "uncool," why are we witnessing (at least anecdotally) a strong trend in favor of helmeted snow-boarders, as this recent NY Times article suggests?

The real question, from my perspective, is whether society considers riding without helmets to be so dangerous that it would rather reduce the overall amount of cycling than tolerate higher levels of helmet-less cycling. To me, as an experienced cyclist who has been involved in his share of accidents (with two cracked helmets sitting on the shelf), the answer to that question is clear: better not to cycle than to cycle without a helmet. My own rule is never to throw my leg over the bike, if I'm not wearing a helmet. And I impose the same rule on my children.

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