Abstract
<title>Abstract</title> <p>This article advances understanding of the barriers to evidence-informed policymaking on illicit drugs in Southeast Asia. By doing so, it aims both to broaden the range of cases that are used to inform theory on evidence use in policymaking and to assist in the collective process of creating more effective and humane drug policies in Southeast Asia. The study is informed by the policy constellations approach and uses case studies from Indonesia, Malaysia, The Philippines and at the intergovernmental level of drug policymaking in Southeast Asia, with a particular focus on involuntary treatment, decriminalisation of drug use/possession, and the use of the death penalty for drug offences. These case studies use three scoping reviews of 83 documents containing the available research evidence on these policy issues, combined with analysis of 200 policy documents and 54 in-depth interviews with evidence producers, users and intermediaries. Critical realist abductive and retroductive analysis reveals that barriers to evidence use include the security focus of drug policymaking, dissensus on the nature of useful evidence, institutionally structured blockages to evidence use, and political pressures and backlash against evidence use. These barriers are supported by material and vested interests, and by the ethico-political base of patriarchal paternalism that underlies drug policymaking in Southeast Asia. These are not absolute blockages to evidence use to inform policy, but they do shape the use of evidence to by the most powerful policy actors to promote continued support for the ‘drug-free’ ideal.</p>