One of the central questions that Congress will face when tackling immigration reform in the next few months is how to prevent illegal immigration in the future, and that's no easy fix.
So far, legislators have come up with three main ways to combat illegal immigration: One, increase border security. Two, adjust future immigration flows to permit more people to enter legally. And three, make it harder to work in the U.S. without authorization.
The last prong has been tried unsuccessfully in the past. The immigration reform law that passed in 1986 made it illegal for employers to hire anyone in the country without authorization. But enforcement has been spotty and fake documents make it hard for employers to know who is here legally or not.
So how are politicians addressing it this time around? One of the existing options is E-Verify, a federal program that uses a variety of government databases to determine whether an individual is eligible to work legally in the U.S.
At a hearing in the House on Wednesday, powerful lobbies like the U.S. Chamber of Commerce and National Association of Homebuilders backed the program. E-Verify has across-the-aisle political support, too. Conservatives like Rep. Lamar Smith (R-Texas) and Rep. Steve King (R-Iowa) are big fans. So is President Barack Obama: a leaked draft of his immigration reform plan showed that the president wants the program to be mandatory within four years of a bill's passage.
Here's how E-Verify works.
When participating employers hire new workers, they are required to check forms of identification, such as a passport or the combination of a driver's license and Social Security card, and enter employee information into the system via the web. E-Verify then returns an approval or non-approval. If a worker is approved, the employer can wrap things up relatively quickly. If not approved, the system helps them figure out why.
Some large companies are enrolled in the program -- Chipotle, for one -- but its use is still not widespread. Only 10 percent of American businesses use it, according to a January report by the Migration Policy Institute.
The program does a good job of identifying legal workers. In the 2012 fiscal year, 98.7 percent of all employees put through the system were confirmed within minutes or within 24 hours, according to Soraya Correa, an assistant director at U.S. Citizenship and Immigration Services who testified at the House hearing.
But when it comes to delivering on its main purpose -- flagging people who aren't authorized to work in the U.S. -- it has missed the mark in the past.
A government report that examined 2007 and 2008 data said the program missed 54 percent of unauthorized workers, primarily as a result of identity fraud.
USCIS has been working to combat fraud, adding a tool that can cross-reference the photo on an applicant's identification card with the photo on record in existing databases. But a request to the agency asking whether the program has made improvements in identifying unauthorized workers went unanswered.
There's another problem with E-Verify. The program is 30 times more likely to give a non-confirmation for a naturalized citizen than someone born in the U.S., according to the aforementioned report. That means that legal immigrants, even though they are citizens, are much more likely to experience problems when applying for a job.
Of course, not receiving a confirmation from E-Verify doesn't mean that you're in the country illegally. The employee's information might have been entered wrong, or the government record might not be up to date. With that in mind, the program specifically tells employers to allow an employee to work if the person is contesting the program's results.
Employers are obligated to let employees know if they've failed to receive a confirmation through E-Verify, but an employee has no way of knowing the results of the test independently. Employees do have the option of checking their work eligibility on their own, however. The "Self Check" program allows you to enter your personal information online and verify your work eligibility.
Still, immigrant rights groups see a window for discrimination: an employer may want to fire someone they suspect is in the country without papers. To go a step further, an employer may avoid hiring that person altogether if they fear the person is undocumented.
Emily Tulli, a policy attorney at the National Immigration Law Center, testified at the committee hearing on Wednesday and said that E-Verify shouldn't be instituted until the workforce is fully legalized. Even then, she said the program should come with employee safeguards and a better track record for accuracy.
"Workers who report mistreatment should be treated as whistleblowers," she said in a statement submitted to Congress. "Without significant penalties for employer mistreatment, and strong worker protections, employer misuse flourishes."
This post was updated at 11:38 a.m.