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The marijuana-legalization movement gained a new friend in a high place Thursday when retired U.S. Supreme Court Justice John Paul Stevens said the federal government should allow American adults to possess pot.

Speaking to National Public Radio, Stevens said public opinion on legal weed has shifted noticeably in recent years toward favoring what would essentially be an end to federal marijuana prohibition.

“Recognize that the distinction between marijuana and alcoholic beverages is really not much of a distinction,” Stevens told NPR.

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“Alcohol, the prohibition against selling and dispensing alcoholic beverages, I think ... there's a general consensus that it was not worth the cost. And I think, really, in time that will be the general consensus with respect to this particular drug,” Stevens said.

Stevens, 94, was part of the high court’s liberal arm during his tenure, which ended in 2010.

On Jan. 1, Colorado adults were allowed by a new state law to buy, grow, possess and use marijuana.

In Colorado, pot industry leader Michael Elliott agreed Thursday with Stevens’ notion that a decades-long fight by national, state and local law enforcement agencies against the sale and use of marijuana has done more damage than good.

“The United States has fought the war on marijuana for 45 years, and spent over a trillion dollars. And even though the United States now has the highest incarceration rate in the world, marijuana is still universally available, particularly in our schools,” said Elliott, executive director of the Marijuana Industry Group, a trade association.

“While the vast majority of Americans agree that the war on marijuana has been a failure, credible alternatives have been lacking,” Elliott said. “Colorado is now showing the rest of the country marijuana reform actually enhances freedom, revenue, and safety … We reject the model of alcohol prohibition, where criminals like Al Capone dominate the market through violence, corruption, and fear.”

- NBC’s Pete Williams contributed to this report