By Will Grant
BBC News, Miami
A federal judge in the United States has ruled as unconstitutional a tough anti-illegal immigration law in the town of Hazleton in Pennsylvania.
Mayor Louis Barletta has vowed to appeal against the ruling
Judge James Munley said the law denied rights granted to everyone in the US, whether legally resident or not.
Businesses employing illegal workers would have had their trading licences suspended, while landlords renting to undocumented immigrants faced fines.
The ruling could affect several similar laws awaiting approval across the US.
The Illegal Immigration Relief Act in Hazleton was one of the most controversial immigration laws in the US.
It was passed last year by the town's Republican mayor, Louis J Barletta, who was hailed by conservatives for his tough stance on the issue.
The law introduced much tougher workplace-enforcement measures, threatening businesses which employed undocumented immigrants with closure.
Also, in perhaps the most controversial part of the act, it imposed fines on landlords who rented their property to illegal immigrants.
Illegal immigrants have been criticised by local residents
Mayor Barletta has been quoted as saying he wanted to make Hazleton the most difficult town in the US for illegal immigrants to settle.
However, on Thursday Judge Munley deemed Hazleton's law unconstitutional.
Even if it did not conflict with federal law, the judge said, the town could not deny rights granted under the constitution to everyone inside the US, whether they were there illegally or not.
The decision has been met with anger by conservatives, who blame the immigrant population for an apparent increase in crime in the small town and for putting a strain on local services.
Mayor Barletta has vowed to appeal against the ruling.
He called the decision bizarre, saying the judge had protected the rights of people illegally in the country.
The outcome will be watched carefully by both sides of this polarised debate.
Similar legislation is pending in dozens of communities and municipalities in the US, and the decision over Hazleton could have ramifications across the country.