It was July 2014 and Jaclyn von Harz and her husband, Jim, knew their 3-year-old daughter Cecilia —whose right lung was filled with cancerous tumors — didn’t have much time or fight left in her tiny body.

“She was just so emaciated,” Jim tells PEOPLE in a story in this week’s magazine. “She’d lost all her hair, lost all her weight. There just wasn’t much of her left.”

Cecilia, it turns out, survived her battle with cancer, but that was only after her parents took the biggest risk of their lives — opting to discontinue her chemotherapy and turning to a drug that has been off-limits to doctors and researchers for the past 80 years: marijuana.

“When your child is sick,” explains Jaclyn, 35, “you get this instinctual feeling. I didn’t know that this would work, but I knew the other alternative would lead to death.”

The von Harz’s agonizing medical journey — along with that taken by several other families desperate to keep their children alive while battling cancer — is told in Weed The People, a new documentary by former talk show host Ricki Lake, focusing on medical marijuana and its use in pediatric cancer.

RELATED: Parents Turn to Marijuana to Cure Their Kids’ Cancer in Ricki Lake’s Weed the People Doc

“This isn’t fringe science anymore,” says Los Angeles pediatrician Dr. Bonni Goldstein, an expert in cannibinoid therapy who worked with the von Harz family. “Studies have shown that cannabis can help kill cancer, in conjunction with chemotherapy, and also help fight the side effects of chemo.”

Adds Lake — who spent six years working on the documentary with director Abby Epstein: “Cannabis (marijuana’s scientific name) needs to be accepted and understood as a medicine. This is a human rights issue and everyone should have access to this plant if they need it.”

RELATED: Olivia Newton-John on Being a Cancer ‘Thriver’ and Using Weed to Cope with Her Relapse: It’s a ‘Healing Plant’

But as many in the medical community have grown open to marijuana’s use as a cancer therapy, it remains illegal, even for medical use, in 19 states. The federal government has designated marijuana as a Schedule 1 drug, meaning one with high potential for abuse.  And the American Medical Association, while acknowledging anecdotal evidence of the drug’s efficacy with cancer patients, insists there is still a need for “scientifically valid and well-controlled clinical trials … to assess the safety and effectiveness” of cannabis in medical uses.

Cecilia’s parents first began giving their daughter tiny doses of the oils extracted from the marijuana plant to ease the debilitating effects of chemotherapy following her initial surgery — to remove a two-pound tumor from her right kidney — in April 2013. The oils contained the compounds THC, which gives the plant its “high,” and the non-intoxicating, powerful anti-inflammatory CDB.

“The doctors and nurses were amazed,” recalls Jaclyn. “She would sleep through her chemo.”

But 11 months later, the cancer returned and numerous tumors were detected in her right lung. Doctors began treating her with radiation therapy and a more powerful form of chemo that quickly wreaked havoc on her weakened body, particularly on her liver.

Her parents were soon convinced the treatment would kill her before the cancer did.

That was when the von Harzes opted to stop the chemotherapy and instead, working with Dr. Goldstein, start Cecilia on higher doses — 400 mg. a day — of both the THC and CBD oils.

“We were scared to death,” says Jaclyn. “But this was our one and only chance to save our daughter.”

Three months later, in October 2014, they began to see results. Scans revealed Cecilia’s tumors had either disappeared or greatly shrunk in size — and she’s shown no sign or symptoms of the cancer since.

“We’ll never know if it was the cannabis,” says Dr. Goldstein, “or the chemo or the combination of the two.”

What’s important to the Von Harzes is that 7-year-old Cecilia is now energetic and healthy — and they’re committed to doing everything they can to keep her that way. “

You can’t put a price on a human life,” says Jim, 37, a Los Angeles firefighter. “I was willing to break any rule, sacrifice my own life and my career for Cecilia — and I’d do it all again in a heartbeat.”