Evidence-based policy making the only game in town?

Katy Wilkinson has made a detailed study of Defra's policy on animal disease, having recently completed her PhD on the subject. She challenges the assumption that evidence-based policy making is the only game in town. In a situation such as we have with bTB, more evidence doesn't seem to help, as it is constantly contested and opposing opinions simply become more polarised. It is in politicians' interests to distance themselves from unpopular decisions, by basing them on "science" and reframing the question as technical one. But, Katy, argued, evidence can only inform decision making, it cannot replace making a decision, as she steered us skillfully through the complicated history of bTB policy.