The image makes supporters of marijuana legalization cringe: a zoned-out-looking, T-shirt-wearing Grateful Dead slacker, his hair long and unwashed and his brain cleansed of any ambition or coherent thought. The caricature is not dissimilar to the distorted images and stereotypes once attached to gay couples. Within the space of just a decade, those unrealistic images of same-sex partnerships quickly disappeared as more Americans embraced their gay colleagues and family members. And with startling alacrity, the law has followed with states adopting same-sex marriage statutes and courts across the country striking down bans on same-sex unions.

Marijuana legalization, its backers say, is the new gay marriage, on an unstoppable path to social and legal acceptance. "It's turned quite quickly," says Erik Altieri, communications director for the National Organization for the Reform of Marijuana Laws. "More and more Americans are waking up to the failure of marijuana prohibition."

Just as gay marriage is becoming the norm, decriminalization and legalization of marijuana is likely to be the law in a majority of states in the near future, Altieri predicts. Decades ago, such a statement would have been laughable.

In past years, the so-called war on drugs dictated that almost no politician or civic leader would dare to advocate loosening laws on pot, which was (and in some quarters still is) seen as a "gateway drug" to other, more damaging substances as well as a source of potentially dangerous impairment on its own. Now, both Colorado and Washington state have legalized recreational use. Nearly two dozen states (and the District of Columbia) have laws either in effect or that will take effect allowing the use of marijuana for medicinal purposes. The district also recently moved another step closer to legalizing marijuana use: Last week, the D.C. Board of Elections ruled that enough signatures had been gathered to put full legalization of pot on the ballot in November. Alaskans will vote on a similar referendum in November as well.

An October Gallup poll showed that 58 percent of Americans believe the drug should be legalized, an increase of 10 percentage points over the previous year and the first time Gallup has ever reported majority public support for legalization. The New York Times recently carried, for the first time, pro-marijuana ads, and ran an editorial calling for marijuana legalization.

Diana Soliwon for USN&WR

The trend has concerned some who are worried that looser laws will increase use by youngsters and abuse by people of all ages. But that worry is being drowned out by other factors: growing public opinion that the drug is no worse than alcohol, and a sense among both taxpayers and state budget writers that the cost of prosecuting marijuana-related infractions is a waste of money and time that could be better spent on other priorities. Colorado has already brought in more than $25 million in tax revenues from pot sales. "They're realizing it's a lifestyle issue. It's not worth getting agitated about," says Robert Calkin, founder and president of the Cannabis Career Institute, a California-based group focused on the business of marijuana. "Pot is something that can be incorporated [into one's life] just like any other herb or supplement. It's not something we need to be alarmed about," he adds. "You need to be just as careful with aspirin."

The laws in both Washington state and Colorado limit marijuana sales to people 21 and older. And the "legalization" applies only to the possession or transfer of 1 ounce or less of marijuana, a regulation that is meant to keep its use under control.

Diana Soliwon for USN&WR

"This is not a choice of whether marijuana is going to be sold in our communities. It is being sold," says Michael Elliott, executive director of the Denver-based Marijuana Industry Group, which advocates for a licensed, regulated marijuana market. "It's a choice of who do you want selling it? Do you want someone using violence and intimidation and a gun, or do you want someone selling it who has passed a background check and done financial disclosures?"

Opponents say it's not that simple. In Alaska, for example, residents are at particular risk, notes Kristina Woolston, a spokeswoman for Big Marijuana Big Mistake, which is fighting the November referendum. "Alaska Natives have higher per capita rates of substance abuse, suicide and high school dropouts. These are incredibly concerning because it does concentrate around substance abuse," she says. Alaska's very geography makes it especially difficult to control the availability of cannabis, she adds.

Michael "Billy the Kid" Kenworthy, right, selects a package of pot for a customer who identified herself as Tracy while conducting a transaction on June 5 in Seattle. Kenworthy works for Winterlife, a pot delivery service which in July said it would deliver only to medical marijuana patients. Ted S. Warren/AP

For example, dozens of Alaskan villages are dry or damp, meaning alcohol is either not sold or is difficult to obtain. But marijuana could easily be brought to such villages, she notes – especially since so much travel in the state is done in small planes, without prior screening by Transportation Security Administration agents.

Further, it's hard for both users – especially young people – and law enforcement to tell if someone is impaired from using marijuana, says Steve Pasierb of the Partnership for Drug-Free Kids. "How do you know how it's going to pan out? Not enough time has gone by to sort it out."

Some studies have shown that since medical marijuana was approved in some states, there has been an increase in drivers found to have smoked pot. However, supporters of looser marijuana laws point out that doesn't mean the drivers were impaired.

Deputy Derrick Morrison watches as a pile of marijuana plants burns behind the Grundy County Sheriff's Department on July 31 in Altamont, Tenn. Dan Henry/Chattanooga Times Free Press/AP

In January, for example, a driver in Colorado slammed his car into police cruisers, and law enforcement said he was stoned. But the driver was also found to have had a very high level of alcohol in his system, which could have been the cause of the collision. Further, opponents note, there's no marijuana equivalent of a Breathalyzer test to determine if someone is too stoned to drive.