Marijuana convert John Boehner -- perhaps better known as the Republican U.S. House speaker from 2011 to 2015 -- said Friday that the federal government "just needs to get out of the way" and allow the legal cannabis industry to flourish in states that want it.

"The world is changing and the federal government hasn't caught up," Boehner said, speaking at South by Southwest.

A one-time steadfast opponent of marijuana legalization during his time in Congress, Boehner joined the board of advisors of cannabis company Acreage Holdings last year, saying Friday that his opinion of marijuana has evolved over the years "like a lot of Americans." Acreage CEO Kevin Murphy participated alongside him Friday in a featured SXSW keynote.

But despite his conversion to legalization advocate, Boehner said during the event that he still hasn't tried pot.

"I've never used the product," he said in response to a question. "I smoke cigarettes, I drink red wine (and) I have a little bourbon. Not to say I'll never use (marijuana), but I haven't yet."

Instead, he said his thinking evolved after talking with people who told him how much they've been helped by cannabis. He also said the U.S. cannabis industry is poised for tremendous growth and likely will be larger than the cigarette industry in the next five years.

"We are in the very, very early stages of what is going to be a huge industry," Boehner said. "This industry is going to grow exponentially over the next 10 to 20 years."

Boehner downplayed his past opposition to marijuana legalization, saying it wouldn't have won approval anyway while he was in Congress because too many lawmakers -- most of whom he acknowledged were Republicans -- opposed it. Now, he said, he expects a bill to win approval either this year or next that would provide cannabis companies in states where it is legal with access to U.S. financial institutions and stock exchanges, a big first step toward full federal legalization.

So far, 34 states -- including all four Texas border states -- have legalized marijuana for medical purposes, while 10 states also allow adult recreational use. Texas has been among the holdouts in both regards.

Boehner briefly was heckled at Friday's event, during a discussion of the need for criminal justice reform to help people in jail or who have criminal records stemming from arrests for a substance that now is legal in many places. Boehner responded to the heckler, who criticized his voting record, by saying that he has long supported criminal justice reform.

Acreage holdings, which is based in New York but publicly traded on the Canadian Securities Exchange, invests in the cannabis sector and operates growing, processing and dispensing facilities in 19 states.