Congress has been unable to pass immigration reform, and the Bush administration wants to use Social Security records to look for illegal workers.

But on the state and federal level those measures have been blocked because opponents question the accuracy of government databases and say U.S. citizens and legal residents could be mistakenly singled out and fired.

A law recently signed by Gov. Blagojevich prohibits employers in Illinois from participating in a federal program known as E-Verify. That program allows employers to check online an employee's Social Security number, records from U.S. Citizenship and Immigration Services and photographs.

Last month, the Homeland Security Department filed a federal lawsuit against Illinois arguing the state can't block the federal government from carrying out immigration laws.

Meanwhile, a federal judge in California ruled last week that Homeland Security could not enforce a separate policy requiring employers to fire workers if their Social Security numbers could not be verified within 90 days.

Homeland Security has estimated a 5 percent to 7 percent no-match rate with the E-Verify program, which had been tested across the country and in more than 800 Illinois companies for several years.

Local immigration officials said that only 1 percent of those people contested the discrepancy.

As many as 70 percent of discrepancies found in the "no match" letters the Social Security Administration sent out belong to U.S. citizens or legal residents.

Those odds don't make for effective immigration enforcement policy.

"We all know there's human error in computers," said Marilu Cabrera, regional media manager with the U.S. Citizenship and Immigration Services in Chicago.

"But it's not an automatic you're out," she added.

Not a single U.S. citizen or legal resident should have to justify their right to work.

But the burden falls upon the employee to take a day or more off of work to go to Social Security or immigration offices to prove their work eligibility. Many people may not be able to resolve this under the stated deadlines.

In the best-case scenario, they would work under a cloud of suspicion until they could prove their work eligibility. In the worst-case scenario, they could be fired.

For Homeland Security to encourage employers to fire employees who receive "no match" letters contradicts previous policy.

In 2006, the letters said this "does not imply that you or your employee intentionally gave the government the wrong information about the employee's name or Social Security number. Nor does it make any statement about an employee's immigration status."

The numbers could be mismatched for various reasons -- a typographical error in the employee's name, failure of the employee to report a name change, or a mistake in a W-2 form.

The AFL-CIO, a party to the federal lawsuit to halt the "no match" letters, estimates that as many as 600,000 of its workers could receive the letters and be vulnerable to firing. Nationwide, the letters could be sent to about 8 million workers.

U.S. District Judge Charles R. Breyer ruled that the no match letters "would result in irreparable harm to innocent workers and employers."

The judge is right. We shouldn't use Social Security databases rife with error to enforce immigration laws, especially since U.S. citizens and legal residents could be caught in the crossfire.

It makes more sense to use only federal immigration databases, so an employer can verify if someone's green card is valid. This is a more reliable way to check an immigrant's work status. For U.S. citizens, passports prove your legal status.

Until all the kinks can be worked out of the system, Social Security numbers shouldn't be used as tools of immigration enforcement.

Teresa Puente is a member of the Sun-Times editorial board. This column represents her own views and not necessarily the views of the board.