PHOENIX — A bill the Arizona Legislature passed this week that would hand the state and local police broad powers to enforce immigration law has split police groups and sown confusion over how the law would be applied.

While Gov. Jan Brewer, a Republican, has yet to say whether she will sign the bill into law, on Wednesday a national police group condemned it as likely to lead to racial and ethnic profiling and to threaten public safety if immigrants did not report crime or did not cooperate with the authorities out of fear of being deported.

The police group joined a growing list of organizations and religious and political leaders far from the state's borders urging Ms. Brewer to veto the bill. Her spokesman said that of the 15,011 calls and letters her office had received on the bill, more than 85 percent opposed it.

The law would require the police “when practicable” to detain people they reasonably suspected were in the country without authorization. It would also allow the police to charge immigrants with a state crime for not carrying immigration documents. And it allows residents to sue cities if they believe the law is not being enforced.

Members of the Law Enforcement Engagement Initiative, a group of police leaders pressing for a federal overhaul of immigration law, said they worried that other states would copy Arizona, despite the likelihood that the law will be challenged in federal court.

“Just because it is in Arizona doesn't mean it's likely to remain there,” said George Gascón, the chief of the San Francisco Police Department and a former chief in Mesa, a Phoenix suburb. “We are very concerned about what could happen to public safety.”

The Arizona Association of Chiefs of Police and several sheriffs have also come out against the bill, calling it burdensome and an intrusion into a federal matter.

Most police agencies or jails here already check the immigration status of people charged with a crime, in consultation with Immigration and Customs Enforcement, but the new law would expand that power and allows the police to stop people on the suspicion of being in the country without documents.

The Mexican Embassy released a statement expressing concern that the law would lead to racial profiling and damage cross-border relations.

But some of the largest rank-and-file police groups have come out strongly in favor of the bill.

The Phoenix Law Enforcement Association, the city police department's largest union, has promoted the bill as a “common sense proactive step in the right direction in the continuing battle on illegal immigration.”

The Fraternal Order of Police, which represents 6,500 officers statewide, endorsed the bill but said it had reservations over the potential costs to departments and the lack of training for local officers to identify who might be in the country illegally.

Bryan Soller, the president of the Fraternal Order of Police, said if officers ended up arresting large numbers of illegal immigrants, that could add to already crowded jails and costs. Mr. Soller also said departments were worried about the expense of defending any lawsuits by people contending that the law was not being enforced.

But he said he thought many concerns were overblown. His group initially opposed the bill but endorsed it after language was included that he and sponsors believe give officers discretion to use it, in part to ward off federal civil rights claims.

“Some will go out and use it a lot,” Mr. Soller said. “But you are not going to see them doing things much different from what they do now.”

All sides agree that a federal overhaul to better control immigration would help, and advocacy groups, pointing to the Arizona bill, are pushing lawmakers to act soon. But several people involved in the negotiations in Washington said a federal bill was not close to being ready.

Julia Preston contributed reporting from New York.

http://www.nytimes.com/2010/04/22/us/22immig.html