Noted marijuana enthusiast Bill Maher had little patience on Real Time on Friday for former Rep. Patrick Kennedy's (D-RI) campaign against legalizing the drug.

"It just seems so un-Kennedy like to be against what I said a couple of weeks ago was the new gay marriage," Maher told Kennedy in a one-on-one debate. "It is the next civil rights movement."

Kennedy, son of the late Senator Ted Kennedy (D-MA), is the head of Smart Approaches to Marijuana, which claims on its website that it neither wants to legalize nor demonize marijuana. At the same time, Kennedy has gone on record saying he has data showing the drug "destroys the brain and expedites psychosis," which garnered a chiding from Maher.

"It sounds like you've been hanging around with Nancy Reagan in 1983," Maher said derisively.

"I used to have your position, Bill," Kennedy responded. "I used to think marijuana was no big deal. Everyone in my family had cancer, so I wouldn't begrudge them using marijuana to mitigate the effects of chemotherapy."

Then, he said, he learned "the facts" that having a more permissive environment around the drug would encourage more use by kids.

"Oh, come on. Man, come on, man," Maher answered. "This is like global warming denying. This is the kind of stuff we heard years and years ago."

Kennedy countered by revisiting his argument that marijuana producers would take the lead of tobacco companies if the drug were to become legal and begin targeting younger consumers.

"Your reasoning is adults shouldn't do things because kids might," Maher retorted. "Adults shouldn't have fire or drive cars under that reasoning, too. Kids might do all sorts of bad things. Parents have to stop them and teachers have to stop them. And we made laws that said tobacco companies couldn't target them."

When Maher brought up Kennedy's past addiction issues with prescription drugs Ambien and Oxycontin, Kennedy answered that it "doesn't matter" what drug one takes.

"I don't believe people ought to be incarcerated because of an addiction, and I think that's a problem we have," Kennedy said, before bringing up his membership on the board of the National Institute on Drug Abuse and pointing to its own findings pointing toward factors contributing toward increased usage.

"If you reduce the cost -- which will be the case -- more people will use," Kennedy said. "These are the statistics. I don't want to put something out there that you can contest. All I want is for people to know the truth."

Watch Maher and Kennedy's debate, embedded below via YouTube: