The measures, approved by City Council last month, would have imposed fines on landlords who rent to illegal immigrants and denied business permits to companies that give them jobs. They also would have required tenants to register with City Hall and pay for a rental permit.
U.S. District Judge James Munley, ruling that landlords, tenants and businesses that cater to Hispanics face the prospect of "irreparable harm" from the laws, issued a temporary restraining order blocking their enforcement.
"We find it in the public interest to protect residents access to homes, education, jobs and businesses," he wrote in a 13-page opinion.
Hispanic groups and the ACLU sued Hazleton on Monday, contending the laws violate the Constitution because they trample on the federal government's exclusive power to regulate immigration.
Mayor Lou Barletta, who spearheaded the law, has argued that illegal immigrants have brought an increase in drugs, crime and gangs to the city. The city's lawyers on Tuesday cited a 10 percent increase in crime between 2004 and 2005 as a reason why the ordinances should be enforced.
Munley, however, wrote that the city "offers only vague generalizations about the crime allegedly caused by illegal immigrants, but has nothing concrete to back up these claims."
Hazleton's crackdown, which was announced in June, has received national attention and spurred other towns to pass similar laws, saying that the federal government has not done enough about illegal immigration. Municipal officials view the Hazleton lawsuit and a similar one in Riverside, New Jersey, as test cases.
Witold J. Walczak, legal director of the ACLU of Pennsylvania, hailed Tuesday's decision as an important victory.
"I think what's important is the judge recognized that this ordinance has the potential to cause real harm by costing people their jobs, their houses and requiring children to leave schools," he said.
The judge's restraining order expires Nov. 14. He indicated that he will schedule a hearing on the ACLU's motion for a temporary injunction.
Barletta has said he is convinced the courts will ultimately uphold the law.