The Justice Department on Thursday urged the Supreme Court to stay out of a lawsuit involving Arizona's immigration law, saying lower courts properly blocked tough provisions targeting illegal immigrants.

The state law is a challenge to federal policy and is designed to establish Arizona's own immigration policy, the department's solicitor general said in a filing with the justices. Arizona says the law is an effort to cooperate with the federal government.

One provision requires that police, while enforcing other laws, question a person's immigration status if officers suspect they are in the country illegally. In April, a three-judge panel of the 9th Circuit U.S. Court of Appeals in San Francisco upheld a federal judge's ruling halting enforcement of that and other key provisions in the Arizona law.

Arizona Gov. Jan Brewer is seeking to overturn the judge's decision and wants Supreme Court review of the case, arguing that the issues are of compelling, nationwide importance.