The Congressional Research Service, a nonpartisan agency that writes reports for lawmakers, said in a recent analysis that federal law likely precludes municipalities from enforcing such measures.
The Puerto Rican Legal Defense and Education Fund, the ACLU and other groups filed the lawsuit on behalf of 11 Hazleton residents and business owners and three nonprofit groups. Among the plaintiffs are landlords who says they lost tenants and a Mexican immigrant who says her grocery store and restaurant have fallen on hard times since the ordinance was passed.
They want a judge to declare the ordinance invalid and assess damages against the city.
Hazleton's law has divided the city 80 miles northwest of Philadelphia, with longtime residents supporting Barletta, but many Hispanics opposed.
Barletta said he has gotten thousands of calls and e-mails from around the country from people backing him, and that hundreds have pledged money to fight a legal battle. The city has set up a Web site to accept donations for its legal bills and several law firms have promised to help out, too, he said.
"I believe this will be a landmark case. A line has been drawn here in Hazleton. This will impact cities all across the country," he said.