For nine months, the medicine that Alex Repetski has been giving his three-year-old daughter has been illegal. But all that changed Thursday with a unanimous decision from the Supreme Court of Canada.

Repetski gives his daughter Gwenevere cannabis oil to treat her epilepsy. But under rules in place until this week, that oil has been illegal because medical pot users were only permitted to use dried marijuana.

On Thursday, the court ruled that restricting marijuana users to the dried form infringed on their Charter rights, and said users should be able to choose their method of ingestion.

For Gwenevere, cannabis oil has been life-changing. Repetski says nine months ago, his daughter's seizures were so bad, the toddler could hardly function.

"She couldn't do much, she could barely sit on her own," Repetski told CTV's Canada AM Friday.

Brain scans showed that she was experiencing near-constant seizures at a sub-clinical level, meaning her brain was seizing even when there were no physical sign.

The family had tried eight anti-epileptic medications, but none controlled the seizures. Then Repetski read about cannabis oil and about how one of the chemical compounds in marijuana -- cannabidiol, or CBD -- can help control seizures without causing the typical marijuana high.

The family spoke to their doctors about the treatment, but were told there weren't enough published studies on marijuana for epilepsy. Repetski did his own research, gathering up studies and testimonials.

"And one of the doctors was kind enough to take the time and comb through all of it and decided that while he couldn’t guide us on dosing, he didn't think it would hurt her in any way," Repetski said.

"Nothing else was working, so he gave us a prescription."

Asking his daughter to smoke the marijuana wasn't an option. So Repetski learned how to take the dried marijuana his daughter was allowed to have and create marijuana oil in his kitchen, sending it to a lab to test it for safety. He then began giving a small amount of oil to his daughter orally, three times a day.

Two days after they started on the oil in November, Gwen had a minor seizure. But since then, she hasn't had a single seizure.

Gwen is now bounding ahead in her development.

"She's crawling, she's learning to walk, she's playing with toys, she's feeding herself, she's bothering her brother – her quality of life is 1,000 per cent increased," he said.

Health Minister Rona Ambrose said Thursday she was "outraged" by the court's decision, saying her government maintains that cannabis has never been proven through rigorous scientific review to be either safe or effective.

For the last eight months, the Repetskis had been breaking the law by giving their daughter cannabis oil. But Alex Repetski says he but would do anything to help his daughter. Now that the court has decided that what they are doing is no longer illegal, Repetski says he feels relieved.

"Now that there's no fear of prosecution, it takes a weight off," he said, "and hopefully, it opens the doors to other people having better access, and research."