Here is the abstract for the research paper, as found here.
Many jurisdictions require cyclists to wear bicycle helmets. The UK is currently not one of these. However, an increasing number of interest groups, including the British Medical Association, want to change the status quo. They argue that mandatory cycle helmet laws will reduce the incidence of head injuries and that this will be both good for cyclists (because they will suffer fewer head injuries) and good for society (because the burden of having to treat cyclists suffering from head injuries will be reduced). In this paper we argue against this position. We suggest that cycle helmets may not be especially effective in reducing head injuries and we suggest that the imposition of such a restrictive law would violate people's freedom and reduce their autonomy. We also argue that those who accept such a restrictive law would be committed to supporting further legislation which would force many other groups – including pedestrians – to take fewer risks with their health. We conclude that cycle helmet legislation should not be enacted in the UK unless, perhaps, it is restricted to children.
I think a lot of the issues with cycling helmets stem from the fact that helmet standards, testing and as a result design do not reflect the real world demands of a helmet.
British and European standards require helmets to withstand a free-fall drop from 1.5 metres onto a flat and kerb shaped anvil, at an impact speed of about 12 mph. This is equivalent to falling to the ground from a stationary riding position. Cycle helmets are not designed for impacts with moving traffic, or falling from ones bike whilst moving. (bleow is a video of some testing - thanks to Limar
Lets face it, its not likely that in an accident we will fall off our bike and land vertically onto the top of our head / helmet. Most accidents I see involve impacts to the side of the helmet. It is interesting that car companies try to improve the safety of their vehicles with new models, but I don't know whether helmet companies try to do the same. Indeed I don't know of any helmet companies that tout their products as exceeding standards.