The idea of evidence-based policy has gained increasing prominence. Much research exists on the subject, particularly tackling the evidence-based policy turn and, subsequently, its critique. A plethora of studies have identified the shortcomings of the evidence-based policy ideal and challenged its supposed linearity. This project aims to provide an understanding of the way in which evidence is utilized in policy, and contribute to this debate by enacting an innovative research design. I am proposing a 2x2 comparative approach, which looks at the use of evidence across two domains, drug and prostitution policy, across two countries, Australia and the UK. A case-based qualitative comparative approach has the potential to offer a certain depth while at the same time providing the opportunity for analytic generalisation. I argue that evidence can be a prime focus for analysis of the policy process, and that through its lenses one can appraise deeper theoretical and epistemological questions about the state in late modern capitalism, the relationship between knowledge and ideology, science and politics, science and values, reason and emotion. The labelling of prostitution and drug policy as morality policies exposes the nature of these domains as morally and politically antagonistic, whilst providing opportunity to reflect on the role of morality in filtering understandings of evidence and shaping policy positions.