Joseph Carens characterizes his argument as “minimalist,” and in important senses it is. Its starting point is the conventional view, which Carens’s earlier work famously and strongly contests, that state sovereignty and borders do and should matter and, therefore, that “the state has the right to determine whom it will admit and to apprehend and deport migrants who settle without official authorization.” In addition—and admirably, in my view—he eschews any reliance on the familiar arguments justifying amnesty or non-enforcement on the basis of claims that the state is complicit in irregular migration, arguments that would have made it easier for him to persuade some readers.

Carens’s argument is well-stated and I agree with what I take to be its main conclusions: that amnesty should be available to irregular migrants who have resided in the country for a substantial period of time with “a clean record and a history of employment" that the requisite period of time should give “special weight” to the fact that an irregular migrant has spent her formative years in the country and/or has married a citizen or legal resident; and that the conditions of the amnesty should minimize administrative complexity and discretion by using relatively bright-line rules (except when more individuated facts are needed to protect legitimate social interests, a question-begging criterion not mentioned by Carens).

Carens, however, uses the word “moral” to sanctify his claims. In the absence of a more fully developed moral theory, the word is little more than a self-assuring slogan. To be sure, Carens has attempted to elaborate such a theory in his earlier work. Moreover, he hints at a more fully developed affirmative moral theory by discussing three of the moral arguments that he rejects: that an amnesty is unfair to those waiting patiently in line; that irregular migrants are lawbreakers; and that an amnesty for long-term residents would encourage many others to come without authorization. (I assume that he would consider all three moral arguments, including the last which he presents in a consequentialist form).

But his rejection of these rival moral arguments is not altogether convincing. It is true that “most of those who settle as irregular migrants would have no possibility of obtaining authorized entry.” Morally speaking, however, so what? We do not justify conduct otherwise morally doubtful merely because the actor who wants to engage in it will be frustrated by society’s refusal to allow it.

It is also true that the “lawbreaker” argument fails to distinguish between different levels of moral culpability that society associates with different kinds of illegality, and that we do and should treat speeders differently from murderers. But none of this helps us determine, as a moral matter, how seriously we should take irregular migration—or indeed why, from a moral point of view, we should not call the activity what it manifestly is, “illegal,” rather than “irregular,” an arguably amoral euphemism. Nor does Carens’s discussion of statutes of limitations note an important justification for such statutes: the declining reliability and accessibility over time of evidence. The passage of years may support amnesty but it also increases the risk of fraud by applicants whose factual claims become harder for the government to test as the evidence grows stale or inaccessible. Such potentially widespread fraud poses moral and practical problems that Carens simply finesses with an opaque, inconclusive reference to the French experience.

And it is true that irregular migrants might come whatever the probability of a future amnesty. But it is also true that at the margin, which might be large, the incentives for irregular migrants to come would increase, perhaps significantly. If immigrants can gain legal status simply by managing to evade removal proceedings for just five years, they will be strongly motivated to try their luck by illegally entering or remaining.

Carens’s moral arguments, which I largely accept, do not decisively defeat the three competing moral claims that he discusses, not to mention other moral claims that he does not mention—for example, the harm that such migration may inflict on low-skilled Americans, who are disproportionately black and already severely disadvantaged, or on other immigrants. (This empirical claim is accepted by virtually all labor economists, although again it may not fully resolve the larger policy question).

The same is true of Carens’s discussion of the compelling Grimmond case. He notes that in 75-odd years, the U.S.-born Grimmond “never established a legal right to reside in Britain,” although she knew that she was not a British citizen. We know that she had a legal duty to do so. Did she not also have a moral duty to do so—or to put it another way, is the moral strength of her claim compromised by her failure to establish legal residence during those many decades? The answer may well be yes. There are often, perhaps always, competing moral objections or at least considerations that Carens should acknowledge—even apart from “merely” consequentialist ones to which he gives such short shrift here.

Morality, like God (or is it the Devil?), is in the details. For perhaps understandable reasons, Carens has spared us all of them, except the conclusions mentioned above, and a proposal for a five-year residence requirement. Consider, however, the other specific considerations for amnesty that the United States might include in some form: the number of participants and the criteria for eligibility, a “touchback” provision requiring them to return to and live in their home countries before reentering the United States, the status of their family members, payment of a fine, a path to citizenship, the differential treatment of undocumented farm workers, special status for certain applicants such as undocumented youths who graduate from high school or join the military, and many more. Carens is not obliged to discuss the details in this context, but they are all morally freighted and thus, from a moral point of view, could affect the force of his overall argument. In my view, one who would justify amnesty from a moral-philosophical point of view cannot properly say “let the lawyers sort out the details.”

I think there is an overwhelming case for granting amnesty as a matter of legislative grace. Whether it is also morally required, as Carens argues, is far less clear to me.