It is commonly assumed that states have a right to broad discretionary control over immigration, and that they may decide almost in any way they choose, who may stay within the territory and who must leave. But even supposing that there is such a right, we may ask the decidedly moral
question about how it may be exercised. And this query calls us to try to bring our views about the ethics of immigration into equilibrium with our other moral convictions about citizenship, liberty, and equality. Can our common views and practices concerning immigration be rendered consistent with these deeper commitments?
In The Ethics of Immigration
(Oxford University Press, 2013), Joseph Carens
argues that our common commitment to democratic principles requires us to revise much of our thinking about immigration. Beginning with the uncontroversial practice of granting citizenship immediately to those born within a country's territory, Carens argues that claims to social membership and thus to citizenship strengthen as individuals stay in a state; consequently, there is a point at which not extending citizenship to those living within a state's borders is grossly immoral
, even for those who have settled without the state's permission. Carens' arguments about the moral constraints on the state's rights to exclude eventuate in an argument in favor of open borders.