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 the measure violates the law and asked a federal judge to prevent its enforcement.

Hazleton's ordinance inspired nearly a dozen local governments in eastern Pennsylvania — and several more throughout the nation — to consider their own laws on illegal immigration.

Local officials see the Hazleton lawsuit as a test of their ability to take immigration matters into their own hands.

Mayor Lou Barletta proposed the ordinance after two illegal immigrants were charged with shooting and killing a man.

It is not clear how many illegal immigrants live in Hazleton, but the city's Hispanic population has soared in recent years. The mayor said the measure has already prompted some illegal immigrants to leave.

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.

The Congressional Research Service, a non-partisan agency that writes reports for lawmakers, said in a recent analysis that federal law probably precludes municipalities from enforcing such measures.