Professor Carens's paper displays all of the qualities that make him one of the most interesting applied political philosophers writing today. It is unfailingly lucid, engages with a significant issue in real-world politics, and does so from a liberal and humane perspective that makes it hard to dissent from many of his practical proposals for the treatment of unauthorized immigrants. I wonder, nevertheless, whether he has flamed the issue in quite the right way, and whether there are not deeper questions of political philosophy that go unaddressed. At any rate, I shall try to suggest an alternative perspective that would make some practical difference at the level of policy, although it would not mean rejecting all of Carens's concrete proposals. Carens starts from the reasonable assumption that all democratic states now play host to significant numbers of "irregular migrants" (I shall keep to his preferred terminology), so that whatever position one takes on the wider question of these states' right to control immigration, one has to decide what kind of legal regime should apply to people in this position. In addressing this question, Carens draws to some considerable extent on existing legal practice, although he emphasizes that he is interested in discovering what the law ought to say rather than what it does say--specifically, what rights irregular migrants ought to enjoy in liberal democratic states. This focus on law has the advantage of bringing the discussion down to earth and focusing on particular areas of legal and social policy in which these migrants might or might not be granted rights that other citizens enjoy. But it has the potential disadvantage that it may be less easy to see what grounds or principles are being appealed to when a proposal is made. The reasons that lie behind any particular law are often a mixture of pure principle together with policy goals and practical constraints (in this case, for example, the impossibility of obtaining certain kinds of information about those to whom the law is going to be applied).