PASADENA, CA - JANUARY 10: Dr. Sanjay Gupta attends the CNN Worldwide All-Star Party At TCA at Langham Hotel on January 10, 2014 in Pasadena, California. (Photo by Michael Kovac/WireImage)

In the past year, Sanjay Gupta has made no secret of his support for medical marijuana.

A desire for policy change has always been implicit in that support. But in an exclusive interview with The Huffington Post on Friday, CNN's chief medical correspondent called for full-scale federal legalization of medical marijuana in no uncertain terms.

"In terms of making this legal for medicinal purposes -- yes, and there are both very pragmatic reasons and more subjective reasons for that," Gupta said.

He added that federal legalization of medical cannabis should happen if for no other reason than to address the "ridiculousness of the refugee situation" in Colorado.

"This refugee situation that is developing, I thought it would be a bit apocryphal, I wanted to make sure I wasn’t being led down some false path -- but I met with these families and it is real," Gupta said of the hundreds of families who have uprooted themselves and moved to Colorado to take advantage of the state's permissive medical marijuana laws. The patients who move to Colorado feel compelled to stay because using their medicine across state lines could land them in prison.

"Are you really going to arrest a person for taking their medicine back to their state?" Gupta said. "This is not the society that I think most people would think we are and yet it's absolutely happening. It's heartbreaking.”

Many of those families come to Colorado seeking one medical cannabis strain in particular, given a high profile in Gupta's "Weed" documentary for CNN in 2013. Called "Charlotte's Web," the strain is a high-cannabidiol, low-THC medical variety of cannabis that the nonprofit medical marijuana group Realm of Caring has used to treat more than 300 patients to date.

Seven-year-old Charlotte Figi, for whom the strain was named, used to suffer from hundreds of seizures a week. She was the first child in Colorado to be legally treated with cannabis since medical marijuana was decriminalized. Charlotte's recovery has been miraculous, her mother, Paige Figi, told The Huffington Post. "She is getting a re-do of all the years she was robbed by epilepsy," Paige said.

"The idea that people are able to get their cannabis medicine in one state, but not another, defies some of the core principles of our medical system, which strives for an equality of health care in terms of options," said Gupta.

Last week, Gupta wrote a passionate op-ed for CNN reaffirming his position on the benefits of medical marijuana.

"I am more convinced than ever that it is irresponsible to not provide the best care we can, care that often may involve marijuana," Gupta wrote. "I am not backing down on medical marijuana; I am doubling down."

It was a reiteration of a column Gupta wrote last year in which he admitted he'd changed his mind on weed, apologizing for his earlier dismissal of the drug for medical use. Gupta's piece was shared more than half a million times on Facebook, and his documentary "Weed" caused reverberations at the national level. His opinion on the subject captures so many people's attention not just because he is one of cable news' most recognizable personalities, but because he was also President Barack Obama's first choice to be surgeon general when Obama took office in 2009.

When asked why he felt the need to write a follow-up column just eight months after his initial piece, Gupta said that much of it boils down to science and a strong desire to see patients get wider access to a medicine that is, in many cases, the only one that works for them.

"As with a lot of things, as you start to dig deeper into something, you want to make sure that it continues to hold up, that you’re pursuing threads and that they are leading somewhere," Gupta said. "What I found with medical marijuana was that as I dug deeper, that it all really held up. Not only is it real, the mechanisms by which it works are pretty well described and elucidated by a lot of scientists around the world. The therapeutic benefits have squarely moved out of the realm of the anecdotal into science -- peer-reviewed science."

"It doesn’t get sketchier or blurrier or more opaque, it actually becomes clearer as you dig deeper," Gupta added. "So my focus has been on medical marijuana, and making it available, as a real option, to needy patients."

CNN will premiere the second installment of Gupta's documentary, called "Cannabis Madness," Tuesday night. In it, Gupta takes a close look at the federal laws that classify marijuana as one of "the most dangerous" drugs available, "with no currently accepted medical use."

Twenty states, including the District of Columbia, have legalized medical marijuana, and about a dozen more are considering legalization in the coming years. Yet the substance remains illegal under federal law and is rated, alongside LSD and heroin, as a Schedule I drug, a characterization that Gupta strongly rejects.

"It just doesn’t meet the criteria for Schedule I -- and it never did," Gupta said.

The Schedule I status is why the Obama administration continues to raid medical marijuana dispensaries and prosecute their staff. It's also part of the problem scientists have in obtaining cannabis, and funding, to conduct legal research on the drug in the U.S.

Gupta said the U.S. needs a scheduling system that enables research and makes the medicine available to anyone who needs it, regardless of where they live, and with adequate strain options.

"If you think about this whole story and you substitute in another medicine, other than marijuana, into that exact same story, it would be an outrage -- people would be up in arms about it," Gupta said, referring to the federal government's raids of state-legal medical marijuana dispensaries. "It flies in the face of what I think many state and federal politicians have telegraphed, in terms of the fact that they wouldn't behave this way on this issue and yet it's still happening. For me the real problem is, at the end of the day, it’s of course terrible that these guys are going to prison, but that's exacerbated by the patients out there now that aren't able to get what they need because of it."

Historically, Gupta said, there's a real danger when ideology takes precedence over hard science -- and he believes that's what is happening now with medical cannabis.

"This hypocrisy conjures up for me when I was in medical school, some of our first lessons revolved around when politics or religion trumped science and how dangerous that was," Gupta said. "And I think that's what's happening here -- you have politics trumping science. In past situations, it may have been the position of the Earth in the universe. But now it is real people, their lives, their illnesses in the middle of this. It's incredibly sad.”