Wellman's argument begins with three simple premises: first, legitimate states are entitled to self-determination; second, self-determination includes freedom of association; and, third, freedom of association includes the right not to associate (13). These three are developed into an argument for a deontic right to close the borders against even the most needy would-be immigrant: if a state has adequately pursued its obligations under international justice, it can -- simply by citing its self-determination -- refuse to allow any would-be immigrant to cross into its territory.
I suspect I would get off the boat at the very first step: I'm all in favour of perfectly benevolent and trustworthy aliens taking over our political institutions and ensuring that all individual rights are upheld. It seems a weird kind of fetishism to think that groups, and not just individuals, have fundamental rights or interests (though for my best attempt at playing devil's advocate for this "communitarian" view, see my 'half-pie atomism').
Further, given the existence of poorly-functioning states that trap their populations in poverty and oppression, I have difficulty seeing how we could possibly "adequately pursue our obligations under international justice" without granting those suffering individuals access to better-functioning societies. It at least seems a more historically successful solution than attempting to transform broken societies into functional ones -- though it would of course be wonderful if we could manage the latter, too.
Blake offers a powerful criticism limiting the strength of the alleged "right" to non-association:
Wellman's [view] seems to be that those who are members of a group legitimately care about its future direction, and the admission of new members changes the nature of that group and the policies it is likely to make: "since a country's immigration policy determines who has the opportunity to join the current citizens in shaping the country's future, this policy will matter enormously to any citizen who cares what course her political community will take" (40). But it seems hard to think that these considerations, however weighty, give rise to anything like the strong deontic rights discussed here. Imagine, for example, that the members of one demographic group begin to have children at a rate that alarms the members of a dominant majority. Can a legislative majority, in the name of shaping its country's legislative future -- and preserving a particular form of life -- prevent the members of that community from having babies, through compulsory contraception? Can they simply cite the fact that they do not want these prospective members "entering" the community as a reason to impose this policy?
The answer, of course, is no, which Wellman would readily accept; it would be dramatically unjust for the government to coercively prevent the births. This, however, shows us that the right to control the membership of a country is not the deontic right imagined; it is, in contrast, a right that might sometimes be trumped.
And if reproductive freedom can trump it, I don't see any barrier to thinking that an outsider's needs to escape grave poverty and/or an oppressive political regime should likewise trump any "right" of our nation to obstruct them.
Finally, it's surprising to see "freedom of association" presented as a reason for blocking immigration. For what about an individual citizen's freedom to associate with (e.g. by employing) foreigners? All else aside, even just balancing individual freedom of association against group freedom of (non-)association, I would've thought the individual level to be clearly more important. [There was no mention of this point in Blake's review, but I haven't read the book -- does anyone know if Wellman addresses this objection?]