Come November, voters in California will likely get the chance to decide on whether to make marijuana legal for recreational use.

Supporters of the Adult Use of Marijuana Act say they have collected 600,000 signatures in support of putting the measure on the ballot, well ahead of the 365,880 required by the July 5 deadline. The validity of the signatures must be verified by the California secretary of state's office and county officials throughout the state in order for the initiative to be placed on the ballot.

The measure would permit adults to possess up to an ounce of marijuana and grow up to six plants.

"It will be a game-changer, not just in California, but will send a message, not just in the United States, but around the world," said Lieutenant Governor Gavin Newsom, a supporter of the measure. "We're moving in a new, sensible and mature direction."

But there's also vocal opposition to the proposal. A group including the California Police Chiefs Association, California Hospital Association, California Teamsters and California State Sheriffs' Association has vowed to oppose the measure through November.

They're questioning whether state regulators will be able to effectively control the production and sale of marijuana.

"They've proven that they cannot regulate this criminal activity, this is a lawless industry," said Scott Chipman, Southern California Chair for Citizens Against Legalizing Marijuana.

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