And what of the material improvement in the lives of illegal immigrants themselves? Most illegal immigrants have made a considerable effort to get across the border -- traveling long distances, paying human smugglers, avoiding border guards and Homeland Security Department agents. They make the effort for a reason. Hanson, of the NBER, estimates that illegal unskilled workers from Mexico in the U.S. earn 250% of what they could earn legally at home. That adds up to $170 billion in additional wages -- a considerable proportion of which is sent back to families in Mexico. Not surprisingly, economists such as Hanson conclude that illegal immigration is a strong net positive for global prosperity.

The scale of that impact is enormous. Michael Clemens at the Center for Global Development has calculated that four out of five Haitians worldwide who are living on more than $10 a day are living in the U.S., not Haiti. The most plausible way to get to a decent income if you are Haitian -- not an income that allows a big house or a taste for expensive wines, but one equivalent to three Happy Meals a day -- is to move to the U.S. Lant Pritchett of Harvard University has calculated that if rich countries increased the size of their labor force by just 3% through increased migration, this would add $300 billion to the welfare of citizens of poor countries. Immigration is by far the most powerful tool at our disposal for making the global poor better off.

So at this point it's surely worth asking: How much do we value the negligible-to-nonexistent threat to the livelihoods of a few U.S. citizens against the immense, life-transforming benefits to people born on the wrong side of our borders, people who move here without waiting on an immigration process that pretty much won't let them in legally unless they are already privileged by considerable education and experience? (Even for foreigners with a high school education and a skilled occupation, the chances of getting a visa through the lottery process are 1 in 242.)

The moral question
The macroeconomic argument in favor of employing immigrants, even those without papers, is unassailable. But what about the problem that, absent reform, it's breaking the law to do so? When a law itself prohibits doing the right thing, when it is immoral rather than just annoying or inconvenient, and when breaking that law does no great harm to any others, it is justifiable for people of conscience to choose to break that law. That is close to where we find ourselves with immigration legislation. It limits freedom of movement by immigrants and freedom of choice by employees. It does no good, but it causes considerable suffering. Current U.S. immigration laws have all the moral standing of pass laws in apartheid South Africa.

The moral course of ignoring immigration legislation is being widely followed already, particularly in some of the states that are, on their surface, the most anti-immigrant. For example, a Texas law introduced this year would make hiring an illegal immigrant subject to a fine or two years in jail. But it explicitly excludes home help and gardeners, because, its backers admit, they'd have to lock up much of the state if they didn't.

Given the fact that native-born Americans keep having fewer kids and keep aging, they're going to need some more people around to tend the farms, businesses, golf courses, and rest homes. The cynic would say that's what the good people of Texas have already realized. But perhaps they are doing the right thing because it is, well, the right thing. Perhaps the mass disregard of immigration laws in the state makes Texans the rightful heirs of a civil disobedience movement outlined in the Martin Luther King Jr.'s "Letter from Birmingham Jail." If so, in the spirit of American exceptionalism, let us praise the rank yet noble hypocrisy of the border states.