Hazleton, a city of about 31,000 people 80 miles from Philadelphia, voted last month to fine landlords $1,000 for renting to illegal immigrants, deny business permits to companies that give them jobs, and make English the city's official language.
The Puerto Rican Legal Defense and Education Fund said the lawsuit is the first in the nation against a city that passed an illegal-immigration ordinance. The group and other plaintiffs contend that the Constitution gives the federal government exclusive power to regulate immigration and that the Hazleton ordinance is discriminatory and unworkable.
"It makes every person who looks or sounds foreign a suspect, including those who are here legally," Witold Walczak, legal director of the American Civil Liberties Union of Pennsylvania, said in a statement. "You might as well just paint a target on every foreigner's forehead or a sign saying, 'Please treat me differently."'
Mayor Lou Barletta, who proposed the ordinance after two illegal immigrants were charged with shooting and killing a man, had no immediate comment.
Frustrated by inaction in Washington, many cities and states have passed their own measures to restrict or punish illegal immigrants and those who do business with them. Some local officials see the Hazleton lawsuit as a test of their ability to take immigration matters into their own hands.
The Congressional Research Service, a nonpartisan agency that writes reports for lawmakers, said in a recent analysis that federal law probably 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 say they lost tenants and a Mexican immigrant who says her grocery store and restaurant have fallen on hard times since the ordinance was passed.
It is not clear how many illegal immigrants live in Hazleton, but the city's Hispanic population has soared in recent years.