The campaign to legalize recreational marijuana got a boost earlier this month after a judge overturned the secretary of state’s decision to throw out thousands of petition signatures, potentially paving the way to a vote this November.

As Mainers weigh the prospect of legalized marijuana in the Pine Tree State, many will look to Colorado for answers about how a legal marijuana landscape will look.

Colorado has served as a convenient talking point for proponents and opponents of legalizing marijuana, with one side declaring the state’s burgeoning marijuana industry a success and a boon for state coffers and the other calling it a failed experiment. The legalization of marijuana, however, has been a mixed bag, according to a new report from the Colorado Department of Public Safety.

But with only a couple of years of data, this report marks only the beginning of the effort to understand the effects of legalization in the Rocky Mountain State. And its findings aren’t likely to fit conveniently into the political narrative on either side.

“It is too early to draw any conclusions about the potential effects of marijuana legalization or commercialization on public safety, public health or youth outcomes, and this may always be difficult due to the lack of historical data,” Department of Public Safety analyst Jack Reed wrote in the report.

Colorado teens aren’t using marijuana more than they were before legal sales began.

One contentious point in the recreational marijuana debate is whether it the increased availability of the drug will lead to more teens smoking weed. Marijuana use among 12- to 17-year-olds in Colorado is the highest in the nation, but that’s nothing new. So far, legal marijuana hasn’t had a noticeable impact on teen use, according to National Survey on Drug Use and Health data.

In Colorado, about 12.6 percent of 12- to 17-year-olds reportedly used marijuana in the last 30 days for the combined years 2013 and 2014, a slight uptick from 11.2 percent in 2012-2013, according to the U.S. Office of Substance Abuse and Mental Health Services. Nationally, about 7.2 percent of 12- to 17-year-olds had reported using marijuana in the past month in 2013-2014, virtually unchanged from 2012-2013.

Opponents of legalization point to these data as evidence that teens have become casualties of the push for recreational marijuana, while proponents argue it’s evidence that legalization won’t lead to skyrocketing use among teens.

But the data aren’t sufficient to draw conclusions one way or another because the increase in Colorado teen use isn’t statistically significant, federal statisticians wrote in a 2015 report.

“There doesn’t appear to be a significant increase in teen marijuana use yet that we know of, and that’s a good thing,” said Mike Van Dyke, chief of environmental epidemiology at the Colorado Department of Public Health and Environment.

Nonetheless, Van Dyke and other state public health officials are closely monitoring teen marijuana use as the market matures. As the availability of marijuana grows, Van Dyke noted that public acceptance of the drug could inspire greater teen use.

Van Dyke said the state has taken steps that could reduce this risk, including banning public use of marijuana, and the state Legislature is considering modifying regulations for edibles to prohibit vendors from selling them in shapes — such as animals, fruits or humans — that appeal to children.

In the first year after legalization, Colorado saw hospitalizations for marijuana use spike — particularly among out-of-staters.

A tourism industry has grown around legal marijuana sales, with companies such as My 420 Tours offering curious outsiders tours of the Napa Valley of weed.

But for a growing number of marijuana tourists, a vacation is likely to end with a trip to the emergency room, according to a 2016 study in the New England Journal Medicine.

The statewide rate of out-of-state visitors to emergency rooms for issues related to marijuana use rose from 78 per 10,000 visits in 2012 to 163 per 10,000 in 2014. The rate of marijuana-related emergency room visits for Coloradans also increased, but less sharply, from 70 per 10,000 visits to 101 per 10,000.

One reason why visitors are ending up in emergency rooms is that they apparently are less experienced marijuana users than Colorado residents, who have had access to marijuana for a couple of years and have been targeted by state education campaigns, Van Dyke said. As a result, visitors to the state may overestimate their ability to handle marijuana.

“A lot of people do different things when they’re on vacation,” Van Dyke said. “Some people tend to do it overboard more when they’re on vacation, and that could also be playing a part.”

Colorado police still have their hands full enforcing new marijuana laws, and the marijuana black market has spilled over.

Proponents of legalizing marijuana have argued that it would free law enforcement to focus scarce resources on violent crimes. Indeed, marijuana-related arrests fell 46 percent in Colorado between 2012 and 2014, according to the Department of Public Safety’s report.

As a share of total arrests, marijuana accounted for only 3 percent of arrests in 2014, down from 6 percent in 2012.

“Proponents wanted less arrests and incarceration, and that’s what we’ve seen. But marijuana is still a problem for law enforcement,” Marco Vasquez, chair of the marijuana issues subcommittee for the Colorado Association of Chiefs of Police, said.

While arrests for marijuana possession, for instance, are down, police departments are issuing far more citations for public consumption of marijuana, Vasquez said. In Denver, citations jumped more than 400 percent between 2013 and 2014.

What’s more troublesome for police, though, is cracking down on marijuana being diverted from Colorado to other states. Instead of driving the black market out of business, legalization created new opportunities.

During the first year of legal marijuana sales, police seized an estimated 360 shipments of Colorado marijuana bound for other parts of the country, up from 274 seizures in 2012, according to a 2015 report by the Rocky Mountain High Intensity Drug Trafficking Area, a federally funded agency formed to disrupt drug trafficking.

Seizures of black market marijuana sent through the U.S. mail also doubled from 158 in 2012 to 320 in 2014.

What’s not known is whether this Colorado marijuana is coming from licensed businesses, personal growers or the marijuana black market.

“We believe there is a certain amount of diversion from the legal market, but most of it has come from the unregulated market,” Vasquez said.

Before legalization rolled out in 2014, Colorado implemented an advanced tracking system to prevent diversion of marijuana plants from “seed to sale.” Each marijuana plant is outfitted with radio-frequency identification tag to track it until a consumer purchases it.

But under Colorado law residents can grow up to six marijuana plants for personal use, and this isn’t easily tracked.

Stoned driving also has emerged as an issue for Colorado police since legalization.

The Colorado State Patrol began tracking data on stoned driving in 2014, when it issued 674 summons for people suspected of driving under the influence of marijuana. In 2015, the state patrol saw summons for stoned driving dip to 665.

The Denver Police Department, which also tracks stoned driving data, has seen a small but steady increase in stoned driving from 51 in 2013 to 73 in 2015.

Under Colorado law, it is illegal to drive a vehicle with a THC blood count of greater than 5 nanograms per milliliter. (THC is the primary psychoactive ingredient in marijuana.) But Colorado police are finding it difficult to determine whether a driver is stoned.

“We are still struggling to detect someone who is impaired by marijuana. It’s much easier to determine if someone is impaired by alcohol,” Vasquez said. “We’re breaking new ground here in Colorado.”

The science is not clear about what concentration of THC in the blood results in impairment. Research also suggests that THC concentration in the blood dissipates before impairment wears off, making blood samples an unreliable method for testing for stoned driving, according to a 2016 study in the journal Clinical Chemistry.

Colorado police are testing a number of devices to find an accurate and reliable method to detect marijuana impairment, including one device that measures THC levels in saliva. But none have been adopted yet for widespread use.