As this is written, the prospects for reforming immigration once again seem dim.

Why is that? It is, unfortunately, more mistaken intuition than rational opposition. Oh yes, there are those ranting loudly in the wasteland of drive time talk radio about rewarding illegal behavior or jeopardizing national security. There is a smidgen of credibility in both objections, but not much.

Of course, law is to be observed and respected. And it is understandable that the average citizen hearing about hundreds of thousands of undocumented entries into the United States each year is concerned that something is amiss. But it is a mistake to liken the national border to a back yard lot line. While it is natural to think of illegal immigration as a trespass in disregard of national property rights, in truth, that is an imperfect analogy.

A better one is the human reaction to the Prohibition era. In the 1920s and '30s, the manufacture, sale or transportation of intoxicating liquor was against the law. There was only one problem; it was not against human nature. The result: a massive black market and the transformation of law abiding folks into bootleggers. Man, said Aquinas, is to be brought to virtue --- gradually, not suddenly --- and laws must be drawn in light of what human nature can endure and accept.

It is in the nature of those coming to our shores to seek, through a willingness to work, a better life. In California, where I live, most come from Mexico, where years of corruption and political exclusion have yielded an economy of extreme wealth and extreme poverty. The best solution to reducing the pressure on our border is to facilitate, through diplomacy (an unfortunately diminished art in these bellicose times), economic investment and equity in our neighbor to the south.

But given the present realities, the migrants coming to America are not arriving without purpose. They come because there are jobs here --- especially in agriculture, service industries like restaurants, and construction.

Now, this itself might be a rational source of opposition to immigration if the migrants taking these positions were consistently displacing American workers. In the main, however, this is not true. Our population by virtue of its decreased fertility and concomitant aging is unable to fill the jobs that need to be done. Immigration is often the natural by-product of local demand for labor being fulfilled by global supply. And filling jobs at these basic levels often yields expanded opportunities for citizens. This is something we should applaud, not decry.

There are those genuinely concerned about health and education costs in locations flooded with new immigrants. That is responsible planning, but hardly an insuperable difficulty, since we have a well-established system of federal taxation and spending exactly for the purpose of meeting unusual local needs.

No one complains that New Orleans receives more disaster aid than Lincoln, Nebraska. It would be equally silly to begrudge San Diego and San Antonio the monies needed to meet the needs of extraordinary population inflows.

But what about 9/11 and national security? Obviously, a nation cannot ignore those bent on entering our nation to harm us. But think a moment: Would it be easier or harder to pick out would-be terrorists if lawful immigration better coincided with supply? When lawful immigration is subject to an artificial cap that is but a tiny fraction of those seeking to enter, we invite not compliance, but circumvention, making it all the easier for those posing security risk to blend in with the harmless.

Here, too, the Prohibition era is an apt analogy. Transforming an innocent act, indulging a glass of beer, into a crime invited association with authentic criminals who were engaged in more dangerous racketeering and vice.

It is irrational to oppose lifting the limits on migration that would both meet our economic needs and allow us to concentrate limited border patrols on the most suspect. It is also immoral.

It was my pleasure a few weeks back to host Cardinal Roger Mahony and former Attorney General Edwin Meese to a fulsome discussion of immigration at the National Constitution Center in Philadelphia. The churchman and the lawman were expected to disagree. They largely did not. Attorney General Meese opposes an amnesty of the 12 to 20 million undocumented aliens already here, while the cardinal is more forgiving, but both agreed that it is possible to construct an "earned" path to citizenship.

It is, and the reform that is teetering on defeat supplies one. Here again, the Prohibition example is instructive. After repeal, no one suggested wasting valuable time and money prosecuting those who managed to get a drink during the earlier flawed policy.

Reason aside, "the movement to places of hope is woven into the very fabric of the Bible story," as Cardinal Mahony so eloquently reminded. Those "huddled masses yearning to breathe free" still knock upon our door. Faith, if not self-interest, tells us to be welcoming in giving our answer.

Douglas W. Kmiec is Caruso Chair and Professor of Constitutional Law at Pepperdine University, Malibu, and a columnist with Catholic News Service.