The US Supreme Court has upheld a law in the state of Arizona that imposes penalties on businesses that hire illegal immigrants.
It rejected an argument made by a coalition of business and civil liberties groups that the 2007 law conflicted with federal policy.
Chief Justice John G Roberts said on Thursday that seven states had recently enacted similar laws.
A recent Arizona law widening police powers of search was not considered.
The Legal Arizona Workers Act was challenged by the Chamber of Commerce and the American Civil Liberties Union, with the backing of the Obama administration.
It was intended to tackle the problem of immigrant smuggling by requiring employers to check the status of new workers through a federal database.
Employers found to have violated the law can have their business licenses suspended or revoked.
Chief Justice John Roberts said the law ''falls well within the confines of the authority Congress chose to leave to the states''.
The BBC reports the implications of the ruling could be felt beyond the borders of Arizona.
