Migration is not a new phenomenon in world history, but it has never been so extensive as it is today. Modern technologies of communication make it possible for more people than ever before to imagine living in other societies, even distant societies. Modern technologies of transportation make movement much easier; indeed, it is technically possible to get anywhere in the world in a matter of days, if not hours. And for various reasons, people are on the move. As Michael Trebilcock points out in his essay (Chapter 11), more than 100 million people live outside the states in which they hold citizenship, 18 million of them refugees. More would move if they could.

These developments take on a particular urgency for the affluent liberal democratic states of the West, since resistance to immigration seems to be growing in all of them. In traditional countries of immigration like the United States and Canada, people express anxiety about losing control of the borders and anti-immigrant rhetoric is expressed in mainstream political parties.

In Europe, the situation is even more acute. Millions of people have settled in states other than their countries of origin. Despite the fact that no European country recruits immigrants any longer, more continue to arrive: as spouses and children of those already settled, as refugee claimants, or as entrants without formal authorization. The backlash against immigrants is much greater in Europe than in North America. The United Kingdom, France, and Germany have all seen both violent attacks on immigrants and the rise of political forces that make opposition to immigrants the central focus of their rhetoric and policy proposals.