Background and objective:
Created to achieve the highest attainable level of health for all, the WHO is empowered to adopt international norms to guide Member States (MS). If the adoption of a norm can be an essential step in global health governance, ensuring compliance by MS is equally important if WHO normative leadership is to reach its full potential. How can we evaluate the WHO normative leadership? Answering this complex question calls for an interdisciplinary approach with the purposeful addition of a-mixed method approach.

Methods:
To ensure a global approach to the research question, we designed a novel four-step mixed-method approach led by an interdisciplinary team (scholars from law and social sciences, with clinical experts). Our first step was the building of an initial theoretical framework on the implementation of international norms, based on an in-depth study of the relevant literature. This step allowed us to identify factors influencing state compliance, in order to build an analytical grid for our case studies (second step) and a guide for semi-structured interviews (third step). The second and third steps were conducted in a convergent parallel design, with quantitative and qualitative analysis of WHO references in the domestic law of 7 countries and interviews with key international and national actors.

Results:
Developing a specific design ensures that the research object is thoroughly understood. The interdisciplinary approach improves on the current theories on the WHO normative leadership. Various challenges arose from this mixed method, such as the selection of key actors and the plurality of working languages.

Conclusion:
A comprehensive study of the WHO normative leadership requires a novel mixed-method approach that better captures both legal and governance aspects.