For Consideration: Immigration

To put it simply, immigration controls are controls on people, and it is not possible to control some people without controlling others. More to the point, it is not possible to control outsiders (aliens, foreigners, would-be immigrants) without controlling insiders as well. Immigration controls are not merely border controls but controls on the freedom of the population residing within those borders.

Chandran Kukathas, Immigration and Freedom, p. 1.