A coalition that includes former Facebook President Sean Parker on Monday proposed an initiative that would legalize the recreational use of marijuana in California and place a 15% tax on retail sales of the drug.

Parker, a billionaire who also co-founded the file-sharing service Napster, plans to put millions of dollars behind the proposal, intended for the November 2016 ballot, according to those in the coalition.

“It’s very encouraging to see a vibrant community of activists … coming together around a sensible reform-based measure that protects children, gives law enforcement additional resources and establishes a strong regulatory framework for responsible adult use of marijuana — one that will yield economic benefits for all Californians,” Parker said in a statement.

Lt. Gov. Gavin Newsom endorsed the proposal, calling it a “thoughtful measure” that aligns with the recommendations of a blue-ribbon commission he created to study the legalization issue. [Read more at the Los Angeles Times]