Proponents of a 2016 citizens' initiative in Arizona that aims to legalize marijuana for adults 21 and older filed paperwork with the state on Thursday, the first step in their campaign.

The Marijuana Policy Project of Arizona initiative still has a long way to go before becoming a law. But if it's successful, it would reverse about 80 years of marijuana prohibition in Arizona, raise millions in tax revenue and potentially end black-market sales of the plant.

The downsides: We'll let you know if we think of any.

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Actually, it's hard to have a strong opinion about the measure yet -- the language of the proposed law still needs to be written.

"The goal is obviously the legalization of adult use of marijuana in Arizona," says Andrew Myers, a spokesperson for the Marijuana Policy Project who helped lead the state's successful 2010 initiative legalizing medical marijuana. "Specifics are still up in the air."

Myers, also the executive director of the Arizona Association of Dispensaries, says organizers of the new campaign "want a large, diverse coalition of people involved in the drafting" of the initiative.

He envisions the potential law as similar to the legalization measures Colorado and Washington voters approved in 2012, which resulted in retails shops where any adult can purchase marijuana products. Writers of the Arizona ballot question will learn from the experience in those states how to best roll out the regulations that will guide growers and retailers.

The statement of organization filed by the campaign on Thursday with the state Secretary of State's office will be amended when the text of the ballot initiative is created, Myers says.

A February poll of Arizona voters found that slightly more than half support adult-use legalization.

Much can change in two years that could impact the campaign and the voting public's level of support for it. For one thing, the measure will apparently come even as a federal ban on marijuana continues.

A campaign by a different group to put a legalization measure on the ballot this year was called off in June. The Safer Arizona campaign got a late start and hadn't gathered anywhere near the required number of signatures. Mikel Weisser, the head of that campaign and now the Democratic candidate in the race for Arizona's Congressional District 4, says his group is now focused on helping the 2016 initiative.

The MPP's campaign is starting so early, it can't gather signatures yet: State law requires the initiative campaign to wait until after this year's general election, which is November 4.

The number of signatures to gather can't be decided, either, until after the November election, since it's determined by computing either 10 or 15 percent of the votes cast in the governor's race. The percentage needed depends on whether the initiative will aim to make statutory or constitutional changes. (The medical-marijuana law, and the proposed legalization law, are statutory.)

Roughly, a 2016 initiative would need to collect about 200,000 signatures. It'll take money to pay the signature gatherers needed for such a huge effort, and the major sponsor has already been identified. The Washington D.C.-based Marijuana Policy Project is identified in the statement of organization as the sponsoring organization, meaning the campaign expects to receive more than 50 percent of its funding from the group.

The chairperson of the campaign is Gina Berman, an emergency-room doctor who's affiliated with a local dispensary, and the treasurer is Ryan Hurley, a Scottsdale lawyer for several dispensaries.

The campaign is likely to face some opposition. We asked Bill Montgomery, Maricopa County Attorney, what he thought about Thursday's filing by the initiative campaign:

"The possibility of the Marijuana Policy Project pushing an initiative involving marijuana in 2016 has been expected," Montgomery says, (and maybe he read about that possibility in this blog.) "Pending litigation before Division I of the Arizona Court of Appeals may obviate any such effort. Similarly, a change in federal administrations in 2016 with a commitment to fairly enforcing federal law consistent with any respective oath of office could render any initiative effort equally moot."

The litigation to which he's referring is the White Mountain Health Center vs. Maricopa County case. Montgomery believes if he prevails in this case, which poses the question of whether the voter-approved state law can exist due to an alleged conflict in federal law, the state's medical-marijuana law and everything that goes with it would be canceled. If the state judicial system won't let cancer patients use marijuana in Arizona, they sure aren't going to see a "recreational" law as constitutional.

So far, though, the court system has been much kinder to the will of voters than prohibitionists would like. In late 2012, a judge in the White Mountain case ruled that the state's medicinal-use law didn't conflict with federal law, paving the way for the system of dispensaries now in place in Arizona. Montgomery's appealing that ruling. Briefs in the case are to be filed by each side over the next few weeks.

Despite the hurdles, the overall momentum for legalization in the United States doesn't seem to be waning. A new poll shows that Washington D.C. voters, for instance, strongly support a local measure on the November 4 ballot to legalize marijuana use and cultivation -- but not sales -- for adults 21 and older.

UPDATE: Thursday, September 25. We finally received a quote back from Sheila Polk, who we'd emailed early on Friday afternoon with a request for a comment. The quote was actually part of a anti-marijuana-legalization campaign press release which refers to recent poll numbers suggesting support for Colorado's legalization law has slipped:

"It appears voters are paying attention to the failed marijuana experiment playing out in Colorado," said Sheila Polk, Yavapai County Attorney and member of the Marijuana Harmless? Think Again! coalition. "I believe that Arizona will soundly reject the efforts of out-of-state dark money groups to use our children as lab rats in the legalization movement."

We can't help but wonder -- has Polk railed against "dark money" in Republican elections? But she's right that the MPP's funding is sort of "dark." As the national MPP's site states, "We guarantee that your donation will remain private if it is given to MPP or MPP Foundation." If the Koch Brothers are giving millions to the MPP, nobody will find out.

Couple of other things about her quote: Colorado is hardly a "failed marijuana experiment." Only a politician could spout nonsense like that. Even if much of the news of Colorado's experiment describe a success, not a failure, it's too soon to know how the program affects the state. And as for the "lab rats" comparison, we'll just remind readers that Polk comes from a town that is perhaps best known for a collection of bars called Whiskey Row. Polk apparently believes it's okay for boozers to help pay her taxpayer-funded salary, so she can campaign to keep throwing marijuana users in jail. The hypocrisy astounds.

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