Most examinations of the political consequences of social movements are single case studies that seek to ascertain the determinants of movement success. This thesis instead employs comparative analysis to further the understanding of the dynamics of partial successes and unintended outcomes of mobilisation. Thus, instead of simply asking why movements sometimes fail at achieving their core aims, the main contribution of this thesis is to provide a clearer picture of what happens when movements fail.

To address these issues, I examine the largely frustrated, contentious efforts to reform policies that govern illicit drugs in Brazil, which – following the activists themselves – I collectively call the anti-prohibitionist movement. Anti-prohibitionism challenges the War on Drugs, pointing out its destructive consequences, including violence, human rights abuses, corruption and an overall weakening of democratic institutions. In order to attain greater analytical robustness, I subdivide Brazilian anti-prohibitionism into four units: Ayahuasca Movement; Cannabis Movement; Harm Reduction Movement; and NGO-led Advocacy. Collectively, these four units form a comprehensive picture of the civil society-driven drug policy reform efforts in Brazil in the past four decades.

The thesis develops an original analytical framework to assess the pathways leading to varied outcomes among the four units. Employing a combination of social movement theory and comparative historical analysis, I explain how certain characteristics of social movements, as well as the political scenario in which they operate, generate different forms of impactful failure. From a structural point of view, this investigation improves our understanding of continuity and change within such institutions as prohibition.

The findings show that the extant literature on Latin American social movements requires revision, in order to better understand novel forms of contentious politics in the region. Based on the theory of the regulatory state, I propose and develop a new category of Latin American social movement, which I term regulatory contention. In regulatory contention, social movements make primarily rules-based, rather than redistributive, claims. This, in turn, has effects on important factors such as movement strategy, internal organisation, constituency-building and, not least, outcomes.