The 'drug policy ratchet': why do sanctions for new psychoactive drugs typically only go up?

It has been much more common for drugs to be subjected to tighter rather than looser control as drugs and evidence about their effects have has emerged. We argue that there is in place a drug policy ratchet which subjects new psychoactive substances (NPS) to increasing control through the continuation of historical patterns that involve the attribution to emerging drugs of guilt by three different kinds of association: guilt by deviant association; guilt by lunatic association; and guilt by molecular association. We use our contemporary ethnographic experience of drug policy-making to show how these processes continue to be applied to policy on NPS, alongside selective, narrative use of evidence and the 'silent silencing' by absorption of the concept of evidence-based policy. We show that the drug policy ratchet cannot be justified as an example of the precautionary principle in action, as this principle is itself not rationally justified. We conclude that recognition of the drug policy ratchet and its mechanisms may help researchers and policy-makers to improve regulation of NPS.