San Francisco ? Arizona’s immigration law faced tough scrutiny from a federal appeals panel Monday as the state’s governor appeared in person to support the controversial provision on the day before the election in which she’s seeking her first full term.

The 9th U.S. Circuit Court of Appeals signaled it was ready to toss out the provision of Arizona’s law that criminalizes the failure to carry immigration papers showing lawful residency in the United States.

But the three-judge panel didn’t tip its hand over which way it was leaning on other provisions of the state law that touched off a national furor when Arizona Gov. Jan Brewer signed it April 23. The federal government filed a lawsuit soon after to invalidate the measure.

U.S. Deputy Solicitor General Edwin Kneedler argued Monday that the provisions in question violate laws making immigration enforcement the exclusive domain of the federal government.

Among the provisions at issue is the requirement that police — when enforcing other laws — must question the immigration status of people they have reason to suspect are in the country illegally.

“It’s how the state wants to use its people,” said Judge Carlos Bea, appointed to the bench by President George W. Bush. “The state can turn over an illegal to federal officials.”

Kneedler responded that requiring local law enforcement officials to check the immigration status of everyone they suspect as being an illegal immigrant takes away from their investigatory discretion. He also said the law intrudes upon foreign policy and diplomacy, areas that are left for the federal government.

“If every state did this, we would have a patchwork of law,” Kneedler said.

Arizona’s legislature passed the law after years of complaints that the federal government hasn’t done enough to lessen the state’s role as the nation’s busiest illegal entry point. Its passage ignited protests, with thousands taking to the streets of Phoenix saying the law would lead to racial profiling. The law prompted lawsuits from the U.S. Justice Department, civil rights groups and other opponents seeking to throw it out.