Three immigrants in Georgia are suing to challenge a government program that allows local authorities to enforce federal immigration law, and they are seeking to have the case declared a class action to represent many other immigrants.

Experts say the lawsuit, filed last week in federal court in Atlanta, could be the first to directly challenge the legitimacy of the 287(g) program, which has been used to identify more than 180,000 illegal immigrants for deportation nationwide since 2006.

"I have heard of nobody filing a lawsuit on this, and I would have heard about it," said Charles Kuck, a prominent Atlanta immigration lawyer and past president of the American Immigration Lawyers Association.

The lawsuit names U.S. Immigration and Customs Enforcement director John Morton, Cobb County Sheriff Neil Warren, an investigator for the Georgia Department of Public Safety and other officials as defendants.

A Department of Public Safety spokesman and a spokeswoman for Warren's office said Thursday their agencies hadn't seen the lawsuit and couldn't comment. An ICE spokesman said the agency doesn't comment on pending litigation.

The lawsuit seeks to define the class as "all Hispanic persons who have been or will be restrained and interrogated within the State of Georgia" by local authorities enforcing federal immigration law under an agreement with U.S. Immigration and Customs Enforcement.

As of late September, the 287(g) program had been used to identify 14,692 illegal immigrants in Georgia for deportation in the four years since Cobb became the first county in the state to launch the program, according to ICE. Three additional counties plus the state Department of Public Safety have since signed agreements.