Bisbee, Arizona on Tuesday became the state's first city to legalize civil unions for gay and lesbian couples.

According to the Sierra Vista Herald, the Bisbee City Council approved the ordinance with a 5-2 vote after holding an emotional three-hour hearing attended by more than 100 people.

The former mining community-turned-artist's haven is made up of about 5,600 people.

Voters in 2008 approved a constitutional amendment defining marriage as a heterosexual union.

Arizona Attorney General Tom Horne warned that the ordinance would be unconstitutional and promised to go to court to block its start.

“The only proper way to change a statute is through the Legislature, not through actions of the City Council attempting to change a State statute within its boundaries,” Horne wrote in a letter to the city. “I emphasize that I am not expressing any opinion on the policy of the ordinance. My job is to enforce the laws that exist and I am obligated to respond to complaints from state legislators.”

The conservative advocacy group the Center for Arizona Policy has also threatened to sue the city if it allows civil unions.

Bisbee City Attorney John MacKinnon said he would defend the new ordinance at no charge to the city. Bisbee resident and retired attorney Margo McCartney also offered her services.

The unions would be recognized only within Bisbee's city limits.