Civil rights groups have asked a federal appeals court to prevent the most contentious part of Arizona's immigration law from taking effect.
The coalition is appealing a ruling that sunk their earlier bid to bar Arizona's police from enforcing the provision.
The opponents asked the 9th Circuit Court of Appeals on Friday for an order preventing police from enforcing a requirement that officers, while enforcing other laws, question the immigration status of those they suspect are in the country illegally.
Police have been barred from enforcing the requirement since July 2010.
But a U.S. Supreme Court decision in June upheld the provision and cleared the way for officers to enforce it.
A lower-court judge last week rejected a bid by the opponents to block the provision.
Copyright 2012 Associated Press. All rights reserved.