Three-year-old Dahlia Barnhart was diagnosed with an aggressive form of brain cancer last June. Her mother, Moriah Barnhart, immersed herself in research and sought out any treatment that could improve Dahlia’s condition.

"We were pretty much confronted early on with the fact that this was the worst case scenario,” says Barnhart.

Barnhart’s research led her to CBD extract, a major component of the cannabis plant. Unlike more commonly known THC, CBD doesn’t get patients high. Barnhart says CBD has been extremely effective for Dahlia.

"The first night she took it, she slept through the night for the first time in her entire almost three years of life. She very quickly started to get her appetite back, she was thirsty,” says Barnhart.

Many patients swear by CBD as a treatment for a variety of cancers and other serious conditions like epilepsy. Yet despite the fact that it’s not psychoactive, doctors won’t prescribe it for their patients.

"I was really shocked. To be completely honest, I discussed diets, supplements, and the only thing that could not be discussed was cannabis extract.”

The murky waters surrounding federal prohibition have had a chilling effect on the medical community, and even though CBD may be a viable option for many patients, doctors won’t prescribe it for fear of losing their licenses. Prohibition has also made researching and accessing CBD a difficult task. This is because CBD has been "strained out" over the years as CBD counteracts the psychoactive effects of THC. The Ludwig von Mises Institute’s Mark Thornton says that prohibition can help explain these dimished levels of CBD.

“The war on drugs increases the risk and the penalties of being caught and therefore suppliers have a tendency–a strong desire–to bring in highly potent marijuana,” Thornton says. “All of their efforts are given to driving up the potency of THC in marijuana and as a consequence they’ve also reduced the potency of CBD.”

With marijuana legalization picking up steam and advocates like Moriah spreading the word, many are hopeful that access to strains with higher CBD levels may follow suit.

About 4:30 minutes.

Written and produced by Tracy Oppenheimer, who also narrates. Associate producer is Gabrielle Cole. Additonal camera by Zach Weissmueller and Chad Parish. Graphics by Will Neff.

Scroll down for downloadable versions and subscribe to ReasonTV's YouTube channel for notifications when new material goes live.