With Californians likely to vote as early as next year on legalizing recreational marijuana, a task force headed by Lt. Gov. Gavin Newsom will travel the Golden State in the coming months to help the state think through the issues.

In a new report, the task force says the state should figure out in advance how to keep pot from kids and keep impaired drivers off the road, whether to tax weed by weight or its sales price and how to eliminate a black market.

California is among several states likely to see 2016 ballot measures for legalization, as Colorado and Washington state approved in November 2012. The American Civil Liberties Union convened this commission in October 2013, with Newsom as its chairman, to study the issues around legalization.

“I was supportive of it 18 months ago, and I’m supportive of it now, but let me tell you — there’s a lot of work to do here,” Newsom said Thursday afternoon. “This isn’t going to be easy to implement.”

The commission plans to hold open forums across the state and has launched a website at www.safeandsmartpolicy.org.

Newsom, who already has declared his candidacy for governor in 2018, said he’s involved not for campaign visibility or as a popularity ploy but because “for me this is really a moral and ethical thing.” The current system disproportionately pursues people of color for marijuana crimes and costs the state many millions of dollars each year, he said — a status quo that can’t continue.

Legalization “is likely to happen, and on our watch,” he said, so it’s better to carefully craft policy beforehand rather than enacting a law that requires years of cleanup afterward — as California has struggled to do since legalizing medical marijuana in 1996.

Voters rejected marijuana legalization in November 2010 as Proposition 19; it got 46 percent support. A few proposed measures failed to gather enough signatures to reach 2014’s ballot.

Yet 53 percent of the state’s adults now support legalization, the Public Policy Institute of California reported Wednesday — the highest level since that poll began asking the question five years ago. Among likely voters, support stands at 55 percent.

It’s an opinion heavily colored by experience: 74 percent of adults who have tried marijuana favor legalization, the poll found, while only 35 percent of those who have never tried it favor legalizing it.

So public support is growing, but so is concern about underage use. The National Institute on Drug Abuse’s 2014 annual survey found 34 percent of 10th graders and 44 percent of 12th graders had used marijuana. But that’s a compelling case for legalization and regulation, Newsom said: “I don’t know of a drug cartel that asks their street dealers to card children.”

The data shows “we’re failing our kids right now, and for those who are opposed to legalization, I’d like to know what they’re for,” he said. “If they’re defending what’s going on in their communities today, that’s a poor excuse for leadership.”

The commission’s report says keeping legal marijuana out of young hands might require a new system of education, counseling and treatment with new policies and roles for schools. Public safety concerns include impaired driving; it’s not as easy to measure marijuana impairment as it is to gauge drunkenness. And the state would have to consider how to deal with those who grow and sell marijuana outside the legal system.

How best to tax recreational pot remains an open question, the report says. It could be taxed as a percentage of retail price, which might not address the product’s quantity or potency. Or it could be a weight-based tax, but that might encourage a race to create products with more potency per ounce. Or, a tax scale could be tied to the product’s concentration of THC — marijuana’s main active ingredient — but that would be hard to administer.

The commission includes more than 20 drug policy, law enforcement and health experts such as Richmond Police Chief Chris Magnus; Dr. Seth Ammerman, a Stanford University expert in adolescent medicine; and Harlan Grossman, a retired Contra Costa County judge, FBI agent and prosecutor.

Josh Richman covers politics. Follow him at Twitter.com/Josh_Richman. Read the Political Blotter at IBAbuzz.com/politics.