This was written long ago. It was true then, it's still true today. (Except in corners of the Internut like here.)

"No scientific investigation can ever lead to the conclusion that a law ought to be passed. Such questions should properly be decided through the political process, the appropriate forum for taking into account disparate interests, values, and alternative approaches....

Discussions on whether to require cyclists to wear helmets would become more productive if everyone would accept that it is well established that helmets substantially reduce risk [emphasis mine] in a crash, and that passing laws making wearing them mandatory would substantially reduce casualties."

-mr. bill