In this book, Mark Monaghan explores the connection between evidence and policy in contemporary society. By contemporary, he means Western ‘rational’ societies with their orientation towards science and knowledge production. In particular, he focuses on the New Labour ‘modernising’ years in UK, illustrating processes through a case-study of the re-classification of cannabis under the Misuse of Drugs Act 1971 (MDA). This is a complex undertaking which he performs adroitly, providing a comprehensive review of key literature on the relation between evidence and policy as well as explaining the MDA and describing the battle of ideas around drugs.

A key tenet of his argument is that the policy process has distinctive features in what he calls ‘politicised’ policy areas. He challenges the view that drug policy shows no respect for evidence. This complaint, commonly voiced in the drugs field, rests on a zero-sum notion of the relation between evidence and policy – that policy is either based on evidence or that it is not – which, he says, is wrong. The situation is more nuanced and complex.

It is true that recently some prominent policy actors have loudly condemned UK drugs policy as not founded on evidence, as much in frustration at being ignored or even denigrated, or because they hold the naïve view that the relationship between evidence and policy should and could be linear. Paradoxically, exhortations to pay more attention to the evidence are made by advocates of starkly opposing views.

Monaghan traverses this complicated field very well, demonstrating a good understanding of both the literature and a wide range of issues, which he explains clearly. The book will be of value to those interested in the evidence−policy relationship and to those interested in drugs policy, but probably the former will find it most relevant. Building on insights from his case study and with a critical look at other models, he argues for a ‘processual model’ which ‘sees the evidence and policy connection, particularly in politicised areas, as being dynamic and in constant flux’ (pp. 148–9). A range of groups compete to shape the policy agenda, but do so with unequal power.

Would this characterisation apply more widely? Monaghan accepts that generalising from one case study is problematic. He sees generalisation as the goal of research and hopes his model could be tested in other areas. In my opinion, models mainly have value as a heuristic device to help in explaining how decisions are made. Monaghan sees his model as applying especially where issues are hotly contested. Given this emphasis on ‘heavy politicisation’, he could have paid more attention to why some issues rather than others become contested and why contests appear at some rather than other times. His definition of politicised issues as ones which ‘lie at the intersection of autonomous disciplinary boundaries’ (p. 6) seems odd: this may be so but is surely not the whole or main factor. And there are many theoretical and methodological contests within disciplines. If this is the key, it would have been interesting to explore more fully the debates regarding drugs between for example neuro-pharmacologists, psychologists and sociologists. He also notes that a key boundary was between the Home Office and the Department of Health, but this is not pursued in much depth. But he does note the role of ideology, entrenched normative beliefs and worldviews, sensationalist reporting, the appearance of partisan groups supporting different positions, a lack of consensus, and competition, conflict and controversy linked to a struggle for power. In these sensitive areas, ‘the political stakes are high and there is intense media scrutiny of policy’ (p. 43). Evidently, drugs policy and the question of cannabis classification do fall into this category but what is it that leads to such furious rhetoric? I would have liked to have seen more on this.

Drawing on analysis of documents and interviews with participants, Monaghan details discussion of cannabis classification in the early years of the twenty-first century. He presents some fascinating material to categorise the protagonists as belonging to radical, rational or conservative camps. His analysis here is at times rather tortuous, but is consistent, well informed and well judged. This account would have profited from greater consideration of the activities of civil servants who mediate these pressures, and analysis of the wider political context within which these debates took place.

The quotations provide insights into the views and experiences of some of the major players in these events. Monaghan refers to the well-known case of Professor Nutt and the ‘scientifically-based scale of harm’ which he and colleagues constructed. He discusses the role this played in the report of the Science and Technology Select Committee 2006 and Professor Nutt's later fall from grace after clashing with two Home Secretaries. Monaghan argues that the Nutt et al. matrix became central to government decision-making when reclassification was being considered but ‘when the political winds changed’ (p. 125) the matrix was dropped, leading Nutt to complain about the devaluing of science, run headlong into conflict with Ministers and thence lose his post as Chairman of the ACMD. While some aspects of this interpretation are open to question, the central claim stands: that attempts to construct an index of harm were part of the technical analysis utilised by those holding an orthodox approach to drugs policy – what Monaghan defines as the rationalist perspective. He demonstrates through this example that evidence alone is not the main driver of policy, neither is it absent from the process – i.e. the situation is complex and contingent. The cries of foul from some ‘rationalists’ that their science/evidence was being neglected are not sufficient to lead to the conclusion that all drug policy is entirely evidence free.

Drug policy and practice covers a much wider area than simply the issue of cannabis classification. Monaghan does not pretend to provide a complete account of UK drug policy-making. But with this rich and thoughtful exploration of an important topic, he succeeds in his ambition to contribute to a more reasoned debate over the use of evidence in politicised areas.