Guest worker programs are set to be a major sticking point in immigration negotiations before Congress. As Ezra noted, the Senate "Gang of 8" deal includes a guest worker program.

Obama's exact position on this isssue is tricky to nail down. His May 2011 immigration framework, for example, called for "a new, small, and targeted temporary worker program for lower skilled, nonseasonal, non-agricultural workers" in addition to the current non-immigrant work visa programs, which include L-1 for employees of multinational companies, H-2A for low-skill agricultural workers, H-2B for low-skilled non-agriculture workers, H-3 for industrial workers, J-1 for cultural exchange participants like au pairs, and H-1B and TN status for high-skill workers.

But in 2007 he voted for an amendment that would have sunset a new guest worker program after five years, which was viewed as a setback for negotiations toward a comprehensive immigration bill that year (Ted Kennedy, a key participant in those talks, voted against the amendment). His latest paper is quiet on the question.

Do they work?

So whatever Obama's position ends up being this time around, which one is right? Are guest worker programs a workable alternative to a pathway to citizenship for some low-skill workers? Most experts argue no. "I find it slightly amazing that the phrase 'guest worker program' still gets used with a straight face in Washington," remarks Boston College political scientist Peter Skerry, who specializes in immigration policy and the politics around it.

The two most-studied guest worker programs are the Bracero Program — a program for Mexican workers coming to the U.S. that was in place from 1942 to 1964 — and the West German "Gastarbeiter" program in the 1960s and '70s, which allowed in workers from Italy, Tunisia, Morocco, Turkey, Yugoslavia, Greece and Portugal. The latter program was mimicked, usually at a smaller scale, in the Netherlands and Belgium as well as in East Germany (whose workers generally came from Vietnam).

Living under Bracero

The most common analysis holds that the programs were far less temporary than initially intended. "Most students of the Bracero Program would argue that they were, in great part, the beginning of our illegal immigrant problem," Skerry explains. Before then, many Mexicans didn't have the information or means to get to the U.S. Bracero both made emigration desirable and provided a ready means.

"They were started in 1942, at a time when Mexico wasn’t that developed, and it wasn’t so easy to get here, in terms of roads and railroads and means of transportation," Skerry continues. "It’s something that has to get opened up, so [Bracero] had the effect of kind of exposing this opportunity to lots of Mexican workers and peasants, and that really helped build these kinds of networks and patterns where people came and moved north to come here and work." Some of those people bolted into the U.S. and never returned.

While the public reputation of the Bracero Program holds that it led to employer abuse, Michael Snodgrass, a Latin American historian at Indiana University who has studied the program, has a slightly more optimistic take. "The more the program has been studied, we’re finding it was not as exploitative as has often been portrayed," he explains. In the early going, in fact, employer abuses were fairly rare due to rigorous enforcement on the part of Mexican consular officials in the United States, who advocated on behalf of the program's participants.

It didn't hurt, Snodgrass adds, that many Bracero participants got their spots as a result of patronage from the Institutional Revolutionary Party (PRI), which ran the Mexican government from 1929 to 2000 (and regained power in last year's elections). PRI had an incentive to make sure its people were treated well. And it used what powers it had. "They had the right to blacklist entire U.S. counties if it was found that growers there were violating the provisions of the initial agreement," Snodgrass tells me. "There are cases of counties from the Delta region of Mississippi, and Arkansas and Oregon being kicked out of the program."

But that only worked when relatively few people were coming across the border. After World War II, their ranks swelled and enforcement of labor standards waned. There just weren't enough Mexican officials to protect that many people."The biggest complaint I’ve heard is that once they got into the United States, the one right they did not have is to leave their employers," Snodgrass continues. "You were assigned to a growers’ association, you didn’t know if you’d harvest cotton in Texas or tomatoes in California. If it was a bad harvest you could make no money, so some decided I’m not going to use the program because of these limitations or I’ll use it to get in and then skip out."

How many stuck around?

Snodgrass notes that many Mexicans used the program exactly as intended, returning home after their stint ended. Some would go to the U.S. for a few months and then return, living off their much higher American wages for the rest of the year. But he concedes, as Skerry says, that some used the program as a way to get in permanently.

That also happened in Germany. Jagdish Bhagwati, an economist at Columbia and the Council on Foreign Relations who has studied the German program, quotes the Swiss-German writer Max Frisch: "We asked for workers. We got people instead." As with Bracero, it proved hard to ensure that all participants used the program in the intended temporary fashion. "Even though the contracts said these people could be sent back, when it came to the crunch, it was impossible to do that," Bhagwati continues. "Even if it was called temporary, it would turn into de facto permanent." Skerry agrees. "People came in on temporary work visas in Germany, and they didn’t go back, like they were supposed to," he tells me.

The current system isn't immune to this kind of gaming. People overstay their visas all the time. And some of those cases end in people going legit, even without a "path to citizenship" along the lines being discussed in Congress. Bhagwati cites a study by Guillermina Jasso, Douglas Massey, Mark Rosenzweig and James Smith that found that about 32 percent of immigrants who were granted legal status in 1996 were previously illegal residents. What's more, 19 percent had entered illegally too, while just 12 percent were overstaying a visa (another 2.22 percent or so were otherwise illegally here; the numbers don't add up perfectly due to rounding). But a guest worker program will, in all likelihood, push that number even higher.