The bill, which passed the State Senate by a large margin on Tuesday, follows what supporters said were threats against officers here after two recent shootings as well as concerns raised byevents in Ferguson, Mo., where Officer Darren Wilson fled his home after being identified as the officer who shot an unarmed black teenager.
After Ferguson, the issue of officer identification has become “one of the most emotional issues in American policing,” said Chuck Wexler, executive director of the Police Executive Research Forum, which conducts research on law enforcement policy and convenes meetings of police leaders.
The Arizona bill has stirred passionate debate in the state. Its proponents, including many police officers, say it will protect officers and their families from harassment or death threats. Opponents call it an unnecessary step that will deepen suspicion of the police among minority groups.
The governor, a Republican, is reviewing the legislation, a spokesman said on Wednesday.
Legal groups and national experts in law enforcement said that they were not aware of a similar law in any other state, but that local disclosure rules and procedures vary widely.
In 2014, the California Supreme Court ruled against the practice of many local police departments of routinely withholding the names of officers in shootings. The court said officer identities could be protected only when there was specific evidence of danger.
In Ferguson, in a sequence of events that the authors of the Arizona bill said they hoped to prevent, officials initially refused to identify Officer Wilson, but then did so days later, citing public records laws. In the end, the officer was not charged with a crime.
Police chiefs in general want to be transparent, said Mr. Wexler, because they know that secrecy makes it seem as if they have something to hide, he said. But they have to worry about officer safety, a concern magnified by the recent killing of two officers in New York and other police murders.
Proponents said the law would provide for a cooling-off period after shootings and possibly prevent disasters. Levi Bolton Jr., executive director of the Arizona Police Association, which represents 14,000 law enforcement officers across the state, said the bill was driven by a “real belief that if we’re not proactive about this, one day we’re going to hear about an officer and his family who were executed because someone was upset.”
But the Arizona Association of Chiefs of Police opposed the bill on the grounds that it takes decision-making power away from the local authorities.
The bill has aroused strong opposition from civil rights advocates, who say it is unnecessary and will breed distrust. They note that under existing rules, agencies already have discretion to withhold officers’ identities on a case-by-case basis to protect their safety.
“I’m hopeful the governor, who is a pragmatic individual, will realize this is not the best that Arizona can do,” said State Representative Reginald Bolding, a Democrat.
“We trust our police chiefs to protect our cities, to make tactical decisions, but this bill says we don’t trust our police chiefs to decide to release officers’ names,” Mr. Bolding said.
“When there is a strain between police departments and the community, it widens the gap by adding an extra layer of secrecy,” he added.
Alessandra Soler, executive director of the American Civil Liberties Union of Arizona, said the bill “raises questions about potential cover-ups and misconduct.”
“Police officers have this extraordinary power,” she said, “and when they decide to use their weapon and to shoot, the public has the right to know who the officer was. That kind of transparency provides the strongest form of oversight,” she said.
But without stronger protective rules, law enforcement agencies are sometimes too quick to identify officers, putting them at unnecessary risk, said John Ortolano, a highway patrol officer and president of the Arizona Fraternal Order of Police, which supports the legislation.
Steve Smith, a Republican who sponsored the bill in the State Senate, said he was prompted to act after a shooting in which an officer’s name was released and a round-the-clock detail had to be assigned to protect his family.
The local authorities often disclose names too quickly because of public pressure or fear of lawsuits, Mr. Smith said, and the legislation would help reduce those pressures. He said that an officer’s record, including previous disciplinary action, could still be released, just not the name.
But Ms. Soler said statutes already in place would make getting some of that information, in particular disciplinary files, difficult to obtain soon after a shooting. She cited a state law that prohibits the release of such records until the officer has exhausted appeals.
Under the Arizona bill, the identities of officers in shootings leading to death or serious injury could not be disclosed for 60 days unless the officer has been arrested or formally charged in the case, or gives his or her consent.