Health allies in the prevention of obesity: the adoption of the Sugar Tax and Front-of-Package food labelling systems in Mexico

How experts and evidence influence policy change is a point of debate in the literature. It is argued that the theorisation of experts’ roles and knowledge utilisation has occurred in separate siloes failing to address experts’ influence on policy change. Two policy process theories focused on policy networks, the Advocacy Coalition Framework (ACF) and Epistemic Communities (ECs), stress the importance of evidence and experts’ role in policy change. They suggest that experts are influential in times of uncertainty (ECs) and can create networks (coalitions) with actors with similar beliefs to influence the adoption of policies that mirror their preferences (ACF). Yet, how networks are formed, how they influence policy change in contested policy areas, and whether networks are maintained post-policy adoption, remain unclear. This research aims to study networks over time to address the identified theoretical gaps. This objective is addressed through an instrumental multiple-case study that analyses Mexico’s Sugar Tax and Front-of-Package food labelling (FOPL) systems policy developments. It draws on 32 semi-structured stakeholder interviews and complementary documentary materials to explain the configuration and influence of networks of experts based on the ACF and ECs. It explores networks over time using qualitative Social Network Analysis. My results suggest that health experts formed a network with a broader set of actors to influence the Sugar Tax adoption. However, in contrast to what theory indicates, the network’s formation beyond shared values and beliefs was enabled by resources provided by an external donor. Networks were also identified in the FOPL systems case. Despite the high level of conflict in the policy area, the influence of experts and the uses of evidence varied between cases. Regarding networks over time, the study finds that at the organisational level, networks remain active in the policy process post-policy adoption.