How and Why “Ideas Travel” in Migration Law and Policy

This chapter provides an introduction to the study of comparative immigration law through the lens of diffusion. The diffusion perspective invites us to ask how and why “ideas travel” across jurisdictions and to trace the complex ways in which states are interacting with one another in shaping their own borders and membership boundaries. We refer to diffusion as the process through which policy choices in one country affect those made in other countries, and the resulting spread and adaption of law and policy across jurisdictions. In Part 1, we take a transdisciplinary approach to identify several explanatory mechanisms and provide a categorization of rationales that may lead law and policymakers to look “elsewhere” as they contemplate which changes and policies to adopt “here.” In Part 2, we set out several case studies to contextualize and illustrate the themes discussed in Part 1. First, we elaborate on patterns of diffusion that create a “race to the top” as states compete to lure sought-after migrants, including the highly skilled, and, increasingly, the ultra-rich as well. We then shift the focus to the diffusion of restrictive border control policies which create a “race to the bottom” as states compete to deter asylum seekers and other “undesirable” migrants. Finally, we step back in time to trace the spread of Chinese exclusion laws across white settler states in the late 19th and early 20th century to demonstrate that diffusion has been occurring for as long as states have been attempting to exclude certain migrants while seeking to draw others.