How Their Laws Affect our Laws: Mechanisms of Immigration Policy Diffusion in the Americas, 1790–2010

Why do laws become similar across countries? Is the adoption of similar laws and policies due to factors operating independently within each country? Do countries develop similar rules in response to similar challenges? Or is the similarity of laws and policies due to the interdependent responses that scholars have referred to as processes of policy convergence, transfer, and diffusion? We draw on an analysis of immigration and nationality laws of 22 countries throughout the Western Hemisphere from 1790 to 2010, and of seven case studies of national and international policymaking, to show that policies are often interdependent, even in the domain of immigration law, which scholars have presumed to be relatively immune to external influence. We argue that specific mechanisms of diffusion explain the rise of racist immigration policies in the Americas, their subsequent decline, and the rise of an anti‐discriminatory norm for policies. Most striking among our findings is that at key junctures after 1940, weaker countries effectively advanced an anti‐discriminatory policy agenda against the desires of world powers. We identify the conditions under which weaker countries were able to reach their goals despite opposition from world powers.