In a recent article, Hooper and Spicer make several arguments against legislation that would mandate the use of bicycle helmets. While they present reasonable objections to the utilitarian as well as the justice defence of such legislation, their review of the empirical evidence contains inaccuracies, omissions and a bias in the selection of empirical data. While there are legitimate reasons to argue against mandating helmet legislation, these arguments should still be based on clinically and scientifically sound evidence.

We invoke a triple rationale to rebut Hooper and Spicer's argument against mandatory helmet laws. First, we use the laws of physics and empirical studies to show how bicycle helmets afford substantial protection to the user. We show that Hooper and Spicer erroneously downplay helmet utility and that, as a result, their attack on the utilitarian argument for mandatory helmet laws is weakened. Next, we refute their claim that helmet legislation comprises unjustified paternalism. We show the healthcare costs of bareheaded (...) riding to pose significant third party harms. It follows, we argue, that a utilitarian case for helmet laws can be sustained by appeal to Mill's Harm Principle. Finally, we reject Hooper and Spicer's claim that helmet laws unjustly penalise cyclists for their own health-affecting behaviour. Rather, we show their argument to suffer by disanalogy with medical cases where injustice may be more evident, for example, denial of bypass surgery to smokers. We conclude that mandatory helmet laws offer substantial utility and are entirely defensible within the framework of a liberal democracy. (shrink)