Backers of a measure to legalize recreational marijuana use in Arizona are taking their time to determine what should be in the law and how to thread the needle on the most controversial issues for voters.

The proposal from the "Smart and Safe AZ" campaign won't mimic any of those that have so far been approved in 11 other states, said Stacy Pearson, senior vice president with Strategies 360 in Phoenix, who is serving as the spokeswoman for the effort.

"This piece of legislation started from scratch and is in the process of very carefully maneuvering around the mistakes that have been made in other states," Pearson said. "There are very significant lessons to be learned about what not to do. We understand those and are avoiding them."

Arizonans narrowly rejected a marijuana-legalization measure at the polls in 2016.

It's unclear if more than one measure will attempt to make it to the ballot in 2020, but considering the growth of Arizona's dispensaries, which are funding the campaign, the Smart and Safe AZ measure almost certainly will go before voters.

Eleven states — Alaska, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont and Washington — have approved marijuana legalization. So has Washington, D.C.

Legalizing marijuana brings a bevy of questions, from how many dispensaries should be permitted to whether people should be allowed to grow their own plants at home.

Each of those issues has certain appeal to some voters but also threatens to turn some away.

The backers of Arizona's 2020 initiative are being extra cautious considering the 2016 marijuana ballot measure failed in Arizona by a mere 67,021 votes out of 2.53 million votes cast, or 2.6 percentage points.

"This outreach began by looking at all the statements in opposition to the 2016 campaign, from law enforcement to the medical community to the Chamber of Commerce to education folks," Pearson said.

"We reached out to all of the most vocal opponents and asked what we could do to solve those problems. And we've worked diligently to ensure those solutions will be included in this 2020 initiative."

Illinois is the most recent of the states to approve adult use of marijuana, with the governor signing a bill into law June 25 that allows for adult use of the drug starting in January.

Like Vermont in 2017, the Illinois initiative was done legislatively, rather than at the ballot.

The debates and compromises over that bill might foreshadow the Arizona measure.

Colorado and Washington were the first states to approve legalization in 2012, and the pitfalls they've encountered have provided fodder for legalization opponents.

That includes those in Arizona who used television advertisements criticizing Colorado to help sway voters here in 2016.

The initiative will require 237,645 valid signatures by July 2, 2020 to get on the 2020 ballot.

Here's what to look out for in Arizona's measure when it's introduced, which will likely happen this summer:

1) Number of licenses

This is probably the most important detail in the measure because it determines how visible the industry will be and whether anyone but existing medical dispensary companies will get to participate in the market.

Arizona has about 116 operating medical-marijuana dispensaries, many of them controlled by large, multistate operators like Harvest Health and Recreation Inc. Those companies are financing the measure, and the details face scrutiny for how well it serves them.

Recent history shows that voters care about who benefits from recreational marijuana. In 2015, Ohio voters rejected a marijuana initiative, in part because it was seen as too beneficial to a small group of people. It was funded by 10 investor groups that owned the only 10 sites where commercial marijuana could be grown.

Offering licenses to businesses beyond those already involved in the state's medical program could give the program a free-market appeal, but the prospect of hundreds of dispensaries across the state also may seem unsavory to voters.

Illinois has 55 medical dispensaries, and its new law allows each of them to sell at those locations plus one more. And another 75 licenses will be issued later in 2020, meaning the state's initial program should allow for 185 locations.

Colorado has more than 500 retail marijuana dispensaries. The fact that that number is higher than the number of Starbucks in the state has drawn negative attention towards its program

2) Who gets the tax revenue

One of the selling points of legalizing marijuana is the promise of tax collections to bolster state budget priorities like education. The Arizona measure is sure to include provisions for state taxes.

The question is whether the ballot initiative will prescribe where that money goes and at what rate the industry will be taxed.

Too little taxation would limit this selling point of the measure. Taxes that are too high could drive business toward the black market, which is a complaint in other states such as California.

Tax schemes vary widely across the legalized states. In Alaska, where there is no sales tax, marijuana sales between growers and retailers are taxed at $50/ounce for "mature bud/flower."

Washington state charges a 37% sales tax on marijuana.

Some states have different taxes for wholesale and retail sales.

3) Employer rules

Will employers be able to fire workers for using the drug?

Among opponents to Arizona's 2016 initiative were major electric companies who said they feared for workplace safety.

Arizona's measure is likely to give employers some ability to regulate their workers' consumption to ward off that type of opposition.

4) Criminal justice reform

Will people in jail or prison today have their charges dropped or sentences reversed? Will the law change the punishment for underage people who are caught possessing or selling the drug?

The law recently signed in Illinois allows almost 800,000 people with convictions for possessing small amounts of marijuana to have their records expunged, according to the Associated Press.

But addressing past convictions is no simple task, and requires any measure to be substantially broader than simply allowing for retail sales and purchases.

5) Home growing

Will people be allowed to grow their own marijuana, and, if so, how much?

The states with legalized use vary on this topic, which seems inconsequential to business but resonates with many marijuana advocates.

In Illinois, lawmakers allowed only people who qualify for the state's medical-marijuana program to grow at home. Law enforcement officials in that state had concerns over regulating a system where home growing was widespread, according to the AP.

6) Driving under the influence

Opponents of legalization are likely to contend that any loosening of restriction of the drug will lead to more impaired people getting behind the wheel of a car.

That was another of the main criticisms of Arizona's failed 2016 measure.

Prosecuting marijuana cases already is tricky because unlike alcohol, marijuana can be detected in a person's blood long after they have used the drug.

Arizona's top court already has ruled that the mere presence of a non-impairing metabolite of the drug in a person's blood is not enough to prove the person was impaired while driving.

The ballot measure could clarify that driving under the influence is illegal and also attempt to explain what evidence can be used to convict people of driving while impaired.

The Illinois law requires law enforcement to annually report the rate of impaired driving as well as any technological developments regarding how to test drivers for marijuana metabolites that can indicate impairment, along with suggestions to improve current laws.

7) Marketing to children

With edible products like gummy bears and gummy worms constituting more of Arizona's medical-marijuana sales, many people are concerned children could accidentally mistake them for regular treats.

Not to mention the overall signal to young people that legalizing the drug sends regarding its acceptability.

Colorado enacted updated rules last year requiring that marijuana products are "not designed to appeal to children," and to prohibit such items from mimicking trademarked products. They also require a variety of disclosures.

Colorado's rules also include a variety of requirements for edible products that place limits on how much of the drug can be sold in a single container.

Other state rules vary widely, from no regulations on packaging and advertising, to detailed prohibitions like those in Massachusetts against cartoons on the package or colloquial references to marijuana in a dispensary logo.

8) Local control is a big factor

Will municipalities have the ability to restrict or prohibit sales? Even if a measure passes with the voters, some communities in Arizona likely will want to keep marijuana businesses out of their town.

If the measure doesn't allow municipal prohibitions, opponents will be sure to raise that point.

Nick Ponder, the legislative director for the League of Arizona Cities and Towns, said his organization will reach out to the initiative backers with those concerns.

Local zoning issues are the main priority for municipalities, he said.

"Our core principle is protecting local control," Ponder said. "That could be up to and including a prohibition. I think we would be more supportive of the local model and them being able to control what is right for their community."

9) Delivery services

Arizona's medical-marijuana program didn't explicitly allow delivery services, but it also didn't prohibit it.

Today, a variety of delivery services are available to patients in the medical-marijuana program, and cities have taken various steps to address them. Some are offered directly by licensed dispensaries, and some are delivery services that work for the various dispensaries.

Patchwork regulations have led to creative business models to deliver in cities even when those municipalities don't want to allow delivery.

A recreational marijuana ballot initiative could define what types of delivery services are allowed. But it's a tricky section of law. California has laid out delivery rules, but that hasn't prevented confusion.

10) Consumption in public spaces

Another concern for municipalities will be how much they can regulate people using the drug in parks and other public places.

"Part of that issue is smoking around public parks and public buildings to the extent it would affect other people," Ponder said.

Reach reporter Ryan Randazzo at ryan.randazzo@arizonarepublic.com or 602-444-4331. Follow him on Twitter @UtilityReporter.