ABSTRACT
Political scientists use theories so that we are able to focus on deeper, recurring patterns in policy development rather than focusing on the particular groups and individuals involved in any given political conflict. In this chapter, we explain the main approaches that political scientists take to explain immigration policies and policy outcomes. Many authors have developed theories about the types of policy outcomes we have seen over time, and the way that politicians have dealt with immigration policy. Why are policies more expansive at particular times and then more restrictive at other times? Factors such as economics certainly play a role in the development of immigration politics, but we point out that the politics of immigration must be understood through the lens of factors like electoral politics, the role of key interest groups, including immigrant voting blocs, and the development of coalitions for or against immigration. The role of the judiciary must be included as well, since policy is often determined by judges who must interpret the laws and the constitution of a country to determine if policies are in line with existing law and are being properly implemented.
