Businesses in the U.S. have a legal responsibility to make sure that their employees have the right to work in this country — in other words that they have either citizenship or legal immigration status.

Since the mid-1990s, the federal government has offered an online system that allows employers to check on their workers’ status. But it’s got some problems.

The system’s called E-Verify, and until recently employers would just check a new hire’s documents when they first came on board.

Because once people had work authorization — for the most part — they kept it.

But the Trump administration has been cancelling the work authorizations for hundreds of thousands of immigrants from Haiti, Cuba, Venezuela, and several other countries.

“People who have had temporary protected status, who have had that revoked, so large groups of relatively recent immigrants,” said Madeline Zavodny, an economics professor at the University of North Florida. 

The impact isn’t limited to just recent arrivals.

“But in some cases, people have been here for decades as well have suddenly lost their legal rights to work and live in the United States,” Zavodny said. “So, what are their employers going to do? I have no idea.”

The Department of Homeland Security issued new guidance this summer encouraging employers using E-Verify to re-check employees from these groups.

Glen Wasserstein is managing partner of Immigration Law Group in DC.

“They're placing a new burden on the employers that they have to keep checking the E-Verify for their current employees to make sure that their status hasn't been changed on the system, which isn't something that was done prior to now,” said Glen Wasserstein, managing partner of Immigration Law Group in DC.

It’s also a problem, according to Wasserstein and other experts, because the agreement that employers sign when they agree to use E-Verify says they can only check employees’ work status when they’re first hired.

“It is unclear because the two seem not to match,” said Emily Dickens, the head of government affairs at the Society for Human Resource Management.

According to Dickens, it’s also not clear if these re-checks are a requirement or just an option. Her group sent a letter to DHS trying to get clarity.

“So, we gotta hear from them what they are going to scrutinize, what are the things that they're looking for? And so, we need clear, consistent and compliance-oriented guidance for them,” said Dickens.

The Department of Homeland Security was contacted for comment but did not respond.

Even if businesses do get that clarity and continue using E-Verify, the system is not particularly reliable.

“The evidence overwhelmingly shows that E-Verify approves most workers who are unauthorized to work in the United States,” said Alex Nowrasteh, a vice president at the Cato Institute.

According to Nowrasteh, it's easy for people to present documents that aren’t theirs and employers often don’t have an incentive to look too closely when they want to make a quick hire.

“It is not an effective means to weed out unauthorized immigrant workers from the labor force,” Nowrasteh said.

A Cato report from a couple of years back found that E-Verify flagged fewer than one in six unauthorized workers.