His research interests focus primarily on international efforts to provide institutional and legal forms of protection to civilians and forced migrants. He is the author of A Right to Flee: Refugees, States, and the Construction of International Cooperation (Cambridge University Press, 2014) which examines the emergence and evolution of norms around refugee protection and which won the 2016 International Studies Association Ethnicity, Nationalism, and Migration Studies Section Distinguished Book Award, and the forthcoming book Protecting the Internally Displaced: Rhetoric and Reality (Routledge, 2018). His co-edited book, with Alexander Betts and entitled Implementation in World Politics: How Norms Change Practice (Oxford University Press, 2014), examines the difficulties in implementing even strongly institutionalized human-centered norms.