The challenge was brought by the U.S. Chamber of Commerce.
At issue in the case is whether Arizona laws are pre-empted by federal immigration laws, a parallel to the separate case brought by the U.S. Justice Department as a challenge to the broader illegal immigrant law in the state. That separate case is now before a federal appeals court, but a resolution of the employer case in the Supreme Court could be a bellwether.
The laws at issue before the Supreme Court require state employers to check the immigration status of job applicants through a federal computer database, although the federal law creating the database makes its use voluntary, and revoke the business license of state companies that hire undocumented workers.
During argument Wednesday, a majority of the justices appeared to support the Arizona laws, SCOTUSBLOG.com reported.
Justice Antonin Scalia championed the state's authority, the report said, in the wake of what he saw as a failure of the federal government to keep illegal aliens out of the country. Scalia cited the broad immigration law enacted by Congress in 1986 assigning to itself the primary role in controlling aliens' employment, but that also let states take action "through licensing and similar laws."
Scalia read that exception broadly, SCOTUSBLOG reported, and was joined by Chief Justice John Roberts and Justice Samuel Alito. Though he did not enter the argument, Justice Clarence Thomas is expected to join them in any final vote.
Justice Elena Kagan, who was U.S. solicitor general last year and in charge of the Justice Department challenge to the broader Arizona law, was not on the bench for the argument Wednesday.
A ruling should be handed down in the next several months.