President Bush has pledged to expend political capital to pass an immigration plan that would legalize illegal aliens currently in the United States as "temporary workers" and import an unlimited number of new workers from abroad--something he reiterated in his State of the Union address. One of his principal arguments has been that such an initiative would enhance America's security by allowing enforcement authorities to focus their efforts more narrowly, by shrinking the haystack that the terrorist needles are hiding in. To use a different analogy, a guestworker or amnesty program would deny terrorists cover by draining the pool of ten million illegal aliens and ensure that an ongoing flow of foreign workers comes through legal channels.

On the surface, this appears reasonable. Terrorists have indeed benefited from our lawless immigration system. A 2002 study by the Center for Immigration Studies found that the 48 Al-Qaeda-affiliated operatives in the United States from 1993 to 2001 had compromised virtually every facet of the immigration system. Mass illegal immigration creates a large market for frau dulent documents, allowing the 9/11 hijackers, for instance, to amass more than sixty U.S. driver licenses. Mass illegal immigration also overwhelms the resources available to law enforcement, creating the conditions whereby Gazi Ibrahim Abu Mezer, a Palestinian who was part of the 1997 conspiracy to bomb the subway in Brooklyn, was actually caught by the Border Patrol but was released into the United States on his own recognizance because of inadequate detention space. Even in a more general sense, the transience created by mass illegal immigration helps terrorists. As the New York Times noted about Paterson, NJ: "the hijackers' stay here also shows how, in an area that speaks many languages and keeps absorbing immigrants, a few young men with no apparent means of support and no furniture can settle in for months without drawing attention."

Nor is this merely a retrospective problem. There are persistent reports of Middle Easterners illegally crossing the Mexican border amid the ordinary mass illegal flow. They are classified by the Border Patrol as OTMs, Other Than Mexicans. Though opponents of strict immigration enforcement frequently claim that no terrorist has sneaked across the border, this is no longer true: Mahmoud Kourani, "a member, fighter, recruiter and fund-raiser for Hizballah", according to the federal indictment against him, and brother of the terrorist group's head of military security in southern Lebanon, was brought to Mexico and then the United States by a smuggling ring specializing in Middle Easterners. Even more disturbing have been intelligence reports, of uncertain validity, that Al-Qaeda has already sent Chechens across the Arizona border and that it has approached a Central American gang called Mara Salvatrucha about smuggling operatives into the United States.

So shrinking the number of illegal aliens living in the United States, reducing the flow of new illegals and generally restoring order to our anarchic immigration system are clearly security imperatives. But can a guestworker program achieve these goals? It cannot. Support for such an approach is premised on two basic assumptions that turn out to be false.

The first assumption is that the Department of Homeland Security has the administrative capacity to properly screen and track millions of currently illegal aliens and millions more new foreign workers. Such an assertion is laughable to anyone with even a passing familiarity with our immigration bureaucracy. Even before 9/11, the old Immigration and Naturalization Service was choking on mass immigration. Last year, Eduardo Aguirre, head of the new agency that handles immigration services, told Congress:

"In any typical work day, our workforce of 15,500 (one-third of whom are contractors) will: process 140,000 national security background checks; receive 100,000 web hits; take 50,000 calls at our Customer Service Centers; adjudicate 30,000 applications for immigration benefits; see 25,000 visitors at 92 field offices; issue 20,000 green cards; and capture 8,000 sets of fingerprints and digital photos at 130 Application Support Centers.

And despite this effort there is still a backlog of four million immigration applications of various kinds."

Rather than identify the mismatch between mission and resources as the reason for this overload, Congress hit upon a massive bureaucratic reorganization as the solution to this and many other problems, leading to the dissolution of the ins. But the construction of the new Department of Homeland Security has proceeded so badly that the Heritage Foundation and the Center for Strategic and International Studies, two Washington, dc-based think tanks, have already provided an outline to reorganize the reorganization.

The result of placing the huge additional demands of a guestworker program onto an already overwhelmed and confused bureaucracy would be massive fraud. During the last large-scale amnesty for illegal aliens, passed by Congress in 1986 as part of the Immigration Reform and Control Act (IRCA), the number of illegals was smaller than today, and the ins was not undergoing any kind of massive reorganization. But there were still several hundred thousand people who were improperly legalized. Applicants claiming to have been farmworkers described harvesting purple cotton, digging cherries out of the ground and using ladders to pick strawberries.

Such fraud is not merely aesthetically distasteful; each step up the ladder of immigration status (from illegal alien to temporary visitor to permanent resident to naturalized citizen) affords terrorists additional leeway and opportunities. Mahmoud "the Red" Abouhalima was legalized under the IRCA amnesty, claiming to be a farmworker, even though he was an illegal-alien cab driver in New York. Only once he had secured a green card was he able to travel freely to Afghanistan and get terrorist training, and return to help lead the first attack on the World Trade Center in 1993.

The second claim of those promoting a guestworker program as a security measure is that it will end--or at least radically curtail--illegal immigration. Tamar Jacoby, a high-profile spokesperson for the president's plan, recently instructed: "Think of it as a reservoir or a river we're trying to channel into a pipeline. The problem isn't the flow: We need the water. The problem is that the pipeline isn't big enough." In other words, there is a fixed amount of foreign labor that the American economy demands, and our immigration arrangements accommodate only a portion of that demand, forcing the rest to come in illegally. If only the illegal overflow were legalized, the problem would disappear.

Immigration, however, is very different from what this image suggests. The labor market is not designed for any specific level of immigration, or even a specific number of unskilled jobs. It is not a static system, but rather a dynamic one that responds to price signals and substitutes factors of production when appropriate. Labor is substituted for capital when the price of labor falls (say, through massive importation of foreign workers), and the opposite happens when the price of unskilled labor rises (say, through consistent immigration enforcement). Of course, this is cold comfort to those employers who have relied on the expectation of continued non-enforcement of the immigration law, and they can be expected to fight efforts to restrict the flow of foreign labor. But this is a political problem, not an economic one. The economy would adjust quite easily to a smaller supply of immigrant labor, and the accompanying disruptions would dissipate in short order.

In fact, not only would the guestworker approach not end illegal immigration, it would almost certainly increase it. The largest flow of illegal immigration in our history before the current wave came during the bracero program, which imported Mexican guestworkers during the 1950s and early 1960s. A similar thing happened after the IRCA amnesty of 1986. This shouldn't be a surprise. Immigration always creates more immigration, whether legal or illegal, because it is driven not simply (or even principally) by wage differences but rather by networks--the family and other connections that prospective migrants use to decide where to settle or whether to move at all. Once illegal aliens are anchored here by legal status, and once new workers arrive from abroad, millions of additional people worldwide suddenly will have a connection in the United States, making immigration here a realistic option, independent of their qualification under whatever new rules we impose.

What, then, would a security-conscious immigration policy look like? A long menu of changes is available, but the first imperative is a commitment to enforce the law. Immigration expansionists routinely claim that our attempts at enforcement have failed, pointing to their preferred policies as more realistic and enforceable. But there has never been any serious, sustained effort to enforce the immigration law. In fact, enforcement attempts by immigration agents are routinely discontinued because of political pressure, with the officials responsible sometimes reprimanded or forced into retirement.

The most responsible approach the president could take toward immigration would be to state unequivocally that the immigration law, whatever it may be, will be enforced across the board, and that those involved in its implementation will no longer be expected to cut corners and look the other way. The result would not be a magical elimination of the illegal immigration problem, but rather a sustained reduction through attrition, as fewer prospective illegals make the trip and more of those already here give up and deport themselves. In this way terrorists would be kept off-balance, their conspiracies interrupted, their sources of cover reduced. A massive amnesty and guestworker program would do the opposite, serving only the interests of our enemies.