Bryan Caplan is so very, very correct:
Once you pay proper respect to public choice theory, however, you cannot simply continue on your merry way. You have to ponder its central normative lesson: Don’t advocate government action merely because a clever-and-appealing policy proposal passes a cost-benefit test. Instead, look at the trendy-but-awful policies that will actually be adopted – and see if they pass a cost-benefit test. If they don’t, you should advocate laissez-faire despite all those shiny ideas in the textbook.