That's the title of an excellent speech by Michael Crichton; it was linked to in the Corner this weekend and, although I think I read it before, it was worth rereading. Crichton has two good points: When scientists have enough evidence for a claim, they don't have to play the "consensus" card; and when science is subverted for political aims, it is dangerous.
A side note on one comment: Crichton asks rhetorically who would come out against banning secondhand smoke. Well, I would, for one. It's always seemed to me that is one of the things that are best decided by a free market. Restaurant A sits beside Restaurant B. A's owner thinks he can make more money by banning smoking in his restaurant and B's owner thinks he can make more money catering to smokers. Left to themselves, without government interference, they'll soon find out.