BOSTON (AP) -- The state's highest court ruled Tuesday that voters can decide the fate of the casino gambling law, throwing the future of casinos in Massachusetts into question.

The unanimous ruling by the Supreme Judicial Court will allow a question calling for repeal of the 2011 law to appear on the November ballot. It also overturns Attorney General Martha Coakley's finding that the proposed ballot question is unconstitutional because it would cause casino developers to lose property without compensation.

The law allows for up to three regional resort casinos and one slots parlor in Massachusetts. The state gambling commission recently granted MGM Resorts International a license for a proposed $800 million casino in Springfield. The two remaining casino licenses have not yet been awarded, while the slots parlor license has been awarded to the Plainridge harness track in Plainville.

Coakley, who is seeking the Democratic gubernatorial nomination, said she was pleased the court had settled the issue.

"Now, with today's decision, voters will have the final say," Coakley said.

Arguing to get the repeal question on the ballot, casino opponents said developers aren't entitled to any compensation because no property or contract rights exist. They also maintained that the state has "police powers" to revisit and revise laws affecting "public morals and welfare" at any time.

In their repeal campaign, opponents said casinos are a predatory industry and their presence would lead to increased crime and gambling addiction and would hurt small businesses near the resorts.

John Ribeiro, chairman of the group Repeal the Casino Deal, said the group will now enter into a new stage of the fight -- by persuading voters to outlaw casino gambling.

"While this ruling marks a huge hurdle now cleared, it's also the firing of the starting gun in this incredibly important campaign," Ribeiro said. "We know Massachusetts can do better than this casino mess."

Proponents of the law point to thousands of permanent jobs and temporary construction jobs that would be created, along with an influx of new tax revenue for the state. The 2011 law imposes a 25 percent tax on gross gambling revenues at the casinos and a 40 percent tax on slots parlor revenues.

Casino developers also have negotiated agreements that promise financial benefits for host communities. MGM, for example, agreed to pay Springfield $15 million in advance payments and an additional $25 million annually after the casino opens. In awarding the western Massachusetts license, gambling commissioners said the company would not have to pay an $85 million licensing fee until the repeal issue was settled.

The Plainville slots parlor is the only facility where construction has actually begun, with an eye toward a June 2015 opening. Eric Schippers, a senior vice president for developer Penn National Gaming, said that the company was disappointed by the ruling but that construction would continue "full steam ahead."

Wynn Resorts and Mohegan Sun are vying for the eastern Massachusetts casino license. Wynn has proposed a $1.6 billion casino along the Mystic River in Everett; Mohegan Sun is pushing a plan for a $1.3 billion complex on land owned by Suffolk Downs in Revere. A commission decision is expected in September.

The law would also allow for a third casino in southeastern Massachusetts.

Associated Press writers Denise Lavoie and Philip Marcelo contributed to this report.