Supporters say the bill promotes constitutional rights and allows people to protect themselves from criminals, while critics worry it will lead to more shootings as people with less training have fewer restrictions on carrying weapons.
The new law is supported by police unions representing rank-and-file officers, who said their best friend on the streets is a law-abiding citizen equipped to protect themselves or others.
The police chiefs group initially opposed the bill but then took a neutral stance after some provisions were changed at their request. Brewer's office also participated in negotiations on changes to the bill.
A Democratic leader, Rep. Kyrsten Sinema, of Phoenix, said the bill deprives law enforcement of a tool "to separate good guys from the bad guys." With a permit requirement, police encountering a person with a concealed gun but no permit had reason to suspect that person was not a law-abiding citizen, she said.
The Arizona Citizens Defense League, a gun-rights group that lobbied for passage of the "constitutional carry" bill, said gun owners foregoing permits still should get training. "The heaviest thing about wearing a firearm is the responsibility that comes with it," the group said.
Arizona's permissive gun laws gained national attention last year when a man openly carried a semiautomatic rifle to a Phoenix protest outside a speech by President Barack Obama.
Nearly all adults can already carry a weapon openly in Arizona, and supporters of looser laws argue that gun owners shouldn't face additional restrictions just because they want to hide the weapon.
The old law of carrying a hidden firearm without a permit was a misdemeanor punishable by up to six months in jail and a fine of up to $2,500.
Forty-five other states require permits for hidden guns, and two states — Illinois and Wisconsin — prohibit them altogether.
Federal law requires anyone buying a gun from a licensed dealer to undergo a background check, but that requirement does not apply to sales by individuals who aren't dealers. Arizona's law won't change that.
Under the Arizona legislation, people carrying a concealed weapon will be required to tell a police officer that if asked, and the officer can temporarily take the weapon while communicating with the person.
More than 154,000 people have permits to carry a concealed weapon in Arizona.
The bill acted on by Brewer was the first attempt to lift the permit requirement to reach an Arizona governor's desk.
Brewer's predecessor, Democrat Janet Napolitano, in 2007 vetoed two related bills. One would have reduced penalties for carrying a concealed weapon without a permit. The other would have allowed a person without a permit to carry a gun largely concealed as long as any part of it or its holster was visible.
Brewer in 2008 signed into law a bill allowing a person with a permit to take a gun into a restaurant or bar serving alcohol as long as the establishment doesn't prohibit it and the person isn't drinking alcohol. Napolitano vetoed a similar bill in 2005.
