Attorney General Martha Coakley, who joined all 11 of the state's district attorneys in opposing the ballot question, said Wednesday she was working to determine exactly what it will require the legal system to do.

"Question 2's passage not only authorizes the decriminalization of small amounts of marijuana, but also establishes a parallel civil regulatory structure that does not currently exist," Coakley said in a written statement. "At this time, we are reviewing all of the implications of the new law and whether further clarification or guidance is needed."

Massachusetts becomes the 12th state in the country to decriminalize possession of small amounts of marijuana. The measure passed Tuesday with 65 percent of voters supporting it and 35 percent opposed.

Under the state constitution, a ballot question approved by voters becomes law 30 days after an election.

The courts have defined the end of an election as the date on which the Governor's Council certifies voting results. That typically happens during the last week of November or the first week of December.

Until the new law takes effect, marijuana possession will still be considered a crime, Coakley warned.

Possession of small amounts of marijuana in the state is now punishable by up to 6 months in jail and a $500 fine.