By Julian Brookes

At least some able-bodied Americans may soon be able to score a bag of weed legally without having to fake a knee injury. In November, voters in three states could approve ballot measures to legalize marijuana, and not just for medical purposes – for getting-high purposes. Then again, they might chicken out, like California voters did in 2010. But sooner or later, and probably sooner, a state will go green.

About half of America will be fine with that. Support for legalization is (no other way to put it) higher than ever, and rising. That's partly demographics – the young are more into pot than their elders, who aren't sticking around. But it's something else, too: The status quo, people are starting to notice, is a total disaster.

The prohibition on marijuana – a relatively benign drug when used responsibly by adults, and a teddy bear compared to alcohol and tobacco – has done an impressive job of racking up racially-biased arrests; throwing people in jail; burning up police time and money; propping up a $30 billion illegal market; and enriching psychotic Mexican drug lords.

But it hasn't stopped Americans from smoking a ton of weed. We're up to 20-30 million users, 6 billion joints a year – and rising. And teenagers, who ideally shouldn't be toking up on a regular basis, say pot is easier to get than beer. "There's that Talmudic principle that a law that's not obeyed is a bad law," says Mark Kleiman, a drug policy expert at UCLA and co-author of the new book Marijuana Legalization: What Everyone Needs to Know. "And I think we're pretty much at that point."

So, let's try another approach, right? Legalization could come in many forms, but all would involve tradeoffs. And no doubt there are all sorts of ways to screw it up. But more power to the first state to give it a shot.

When that happens, expect one of two things – either: the federal government, in deference to democratic principles, will decline to enforce its ban on marijuana, creating space for the state to be a "laboratory of democracy," working out its new policy by trial and error, learning as it goes, creating a trove of hard-earned lessons to guide the states that (inevitably) will follow; or: the federal government will bide its time and then come down hard, busting growers and retailers, seizing land and property (or, just as effective, threatening to), going after banks that serve pot businesses, and doing whatever else it takes to shut down the state's legalization push.

True, the feds would be within their rights to crack down. A state can legalize all it wants, but – incredibly – happy-go-lucky marijuana will still be a Schedule I substance, right up there on the federal shit list with heroin, LSD, and "ecstacy" – substances defined as having a "high potential for abuse" and "no currently accepted medical use."* And, no, this isn't some quaint, disregarded artifact from olden times: A personal stash can get you a year in federal prison, a single plant up to five.

And don't be surprised if Washington does crack down. As a candidate, "Choom Gang" alumnus Barack Obama talked a good game about bringing some sanity and proportion to drug enforcement. But during his term, federal prosecutors (who, in another complication, have wide discretion to pursue their own agendas) have cracked down hard on medical pot providers in states like California where it’s legal. The administration says it's surgically targeting front operations supplying recreational use, but it sure doesn't look like that on the ground. "Obama has been a terrible disappointment," says Keith Stroup, founder of the drug law reform group NORML.

But maybe the federal government will do the right thing and lay off. "There's a strong argument for trying it at the state level and for the feds getting out of the way," says Kleiman. "That seems unlikely, but I'd love to be proven wrong." (If the president in January 2013 is zero-tolerance drug warrior Mitt Romney, run for the hills.)

We might not have long to wait to find out. Of the three states where legalization is up for a vote in November – Colorado, Washington, and Oregon – Colorado "is definitely the best shot so far," says Steve Fox of the Marijuana Policy Project, a national lobby group that's kicking in about $1 million to support the measure. Under Amendment 64, the state would treat pot like alcohol – licenses for producers and sellers, 21-plus age restriction for buyers, and tax revenue government. Should it pass – and one poll has support up by 61-27 – "We're hoping the federal government will not impose its will," says Fox, "and that there'll be an adult conversation about what Colorado has decided to do."

A lot depends on how things play out on the ground, which is hard to predict. A few things we can assume: the price of pot will plummet, since marijuana is incredibly inexpensive to produce if you don’t have to dodge the cops or schlep it up from Mexico. Consumption will surge, though by how much is hard to say (the consensus guesstimate predicts a doubling or tripling). Beyond that, nothing is clear.

Amendment 64 leaves a lot of the policy details to the state legislature, and one of its first tasks will be to figure out how big of a tax to slap on. It has to be large enough to generate revenue – Amendment 64 wisely stipulates that the first $40 million generated will go to public school construction! – but not so large that buyers prefer to take their chances on the (untaxed) black market. Another challenge: How do you do a better job than current policy of reducing teen use? Or combating abuse and dependency – a problem for only 2-3 percent of users, but not something you can ignore. And how do you prevent neighboring states, if not the entire country, from getting buried under mountains of cheap Colorado weed? If the state looks like becoming the nation's grow house, the feds will probably land hard.

Looking beyond this year, bear in mind that there’s more than one way to "legalize" pot. Colorado is going with the alcohol model, but there are other approaches, some more plausible than others. At one end of the spectrum there's full commercial legalization, where anyone can freely produce, distribute, market, sell, or buy pot, just like any other commodity (think: tomatoes) subject to certain regulations. Hard to see that flying politically. At the other end, there's "decriminalization," where you eliminate or reduce penalties for possession (say, to the level of a minor traffic violation), especially for first-time offenders, but retain the ban on production, distribution, and sale; fourteen states, including California and Massachusetts, have already gone this route, and some major politicians, like Mayor Rahm Emanuel in Chicago and Gov. Andrew Cuomo in New York, have lately come around to the idea. Other options include, on the production side, restricting the industry to nonprofits, or membership-based "clubs," or allowing profit-making but limiting or banning marketing and advertising.

There are tradeoffs: Legalize commercially, whether fully or on the alcohol model, and you add to the sum of freedom and pleasure in the world, wrestle an industry away from violent criminals, generate useful tax revenue, and spare a lot of people jail time and criminal records. But brace yourself for a huge upsurge in use and, possibly, a marketing blitz aimed at teens (see tobacco) and the "heavy" users who consume most of the product and therefore supply most of the profits (see alcohol); and say hello to a well-funded pot lobby bent on blocking regulations it doesn't like (see tobacco and alcohol). Decriminalize, and you save a lot of cop time and money and, again, human misery. But you’re leaving a lot of tax revenue on the table and, incoherently, nudging people to buy what's illegal to produce and sell.

Voters will have to weigh these and other factors and decide whether the (not-fully-knowable) benefits of legalization outstrip the (hard-to-anticipate) costs. No plausible scenario is all upside; but it's hard to see how we could make things worse. "We don't say there are no negative consequences to marijuana use, but there are much more effective ways of dealing with those," says Jill Harris of the Drug Policy Alliance, a group that advocates for more liberal drug laws. "It's just that the consequences of marijuana prohibition are just so much more severe that we feel it's worth the tradeoff."

Beau Kilmer, a researcher at RAND and co-author of Marijuana Legalization, says whatever a given state decides to do, lawmakers should make sure to give themselves an "escape clause," like a sunset provision that makes the laws go back to what they were after a certain number of years unless the voters or legislature decide to extend them. "There's no reason to believe they'll get it right on the first or even second try," he told me. But once the pot industry develops some lobbying muscle, the policy will be much harder to tweak. With an escape clause, he says, legislatures will be able to overcome the lobby "just by sitting still."

Of course, the federal government might decide not to tolerate legal marijuana under any circumstances, and all this will be moot. The only way to take the feds out of the mix is to change federal law, and only congress can do that.

But don't expect too much there. Last year, Reps. Barney Frank and Ron Paul introduced the first-ever federal legalization bill. It’s not going anywhere anytime soon; another Frank bill, the Medical Marijuana Patient Protection Act, which would leave enforcement of medical pot to the states, has been kicking around the Hill since 1997, but has never made it to a vote. "Congress is several years behind the general public on this," says Rep. Jared Polis, a Colorado Democrat and a co-sponsor of both bills. But even congress is starting to come around. When he first came to Washington, in 2009, there were only "a handful" of lawmakers prepared to stand up for more liberal drug laws, says Polis. Today, most Democrats are on board.

The GOP, not so much. "I've been very disappointed with my fellow Republicans on this issue," says Rep. Dana Rohrabacher of California, a co-author of the Frank-Paul bill and a rare pro-pot conservative. "I know that if this was a secret ballot, a majority of them would be voting on my side." Rohrabacher says a lot of his states-rights-and-small-government-minded colleagues agree that marijuana enforcement is a huge waste of tax dollars, but they're not willing to go there. "They’re are just terrified that in an election next time around there’ll be ads run against them about how they’re doing the bidding of the drug dealers."

So don’t look to Washington D.C. for action on this any time soon. Legalization, when it comes, will come at the state level. There's no guarantee it will happen this year, but there’ll be more initiatives on state ballots in 2014, and 2016, and beyond. Most pot activists and policy analysts I spoke to put the timeframe for legalization at 5-7 years, tops. "We’re guaranteed to win in the end because we’re winning the hearts and minds of the American public," says NORML’s Keith Stroup.

And then? "If we get state-level legalization and it doesn't turn into a total clusterfuck, we'll see more acceptance," Kleiman told me. In any event, he says, something's got to give. "Prohibition is falling apart, about the way alcohol prohibition fell apart. Legalization is eventually going to be a recognition of the facts on the ground."