"It sets an important precedent to ensure all First Nations children across Canada are given equal access to essential government services," said Paul Champ, the lawyer for the boy's mother.
The case centres around 18-year-old Jeremy Meawasige, who has hydrocephalus, cerebral palsy, spinal curvature and autism, is self-abusive and can only communicate with his mother, Maurina Beadle.
His mother took care of Jeremy full time at their home on the Pictou Landing reserve in Nova Scotia until she had a massive stroke in 2010.
Since then, the band has been footing the bill for the home care and experts required to keep Jeremy at home. But the bill has been overwhelming for the community of 600, eating up 80 per cent of the band's home care budget.
Justice Leonard Mandamin ruled Friday that the federal government was wrong to only cover a fraction of those costs. Ottawa has been contributing $2,200 a month for his care, but the band council was paying out about $8,200 a month, and could no longer afford to keep paying.
"The only other option for Jeremy would be institutionalization and separation from his mother and his community," Mandamin writes.
"His mother is the only person who, at times, is able to understand and communicate with him. Jeremy would be disconnected from his community and his culture."
The ruling says Ottawa is obliged to uphold "Jordan's principle" — an agreement that First Nations children should get the public help they need, regardless of jurisdictional disputes between governments about who should pay.
It is named for Jordan River Anderson, who died in hospital in Manitoba in 2005 while governments bickered about payment of home care services.
Parliamentarians voted unanimously in favour of adopting the principle. While no legislation accompanied the motion, government departments publicly declared they would uphold it in their policies, the ruling notes.
In Jeremy's case, federal officials had argued that they were already providing funding in line with provincial programs. But they didn't take into account provincial provisions for special circumstances, the ruling points out.
"Jordan's principle is not to be narrowly interpreted," Mandamin warned.
He did not say exactly how much the federal government should be paying to the Pictou Landing band council, but indicated that it should be a lot more than the $2,200 it is already paying. Champ said he believes the ruling gives Beadle and the band council grounds to expect a full reimbursement.
The implications for Jeremy's family are enormous, said his 23-year-old brother Jonavan Meawasige. He has had to take on much of the home care over the past two years, while also trying to fish for a living.
"I've been working my ass off," he said in an interview from the family home. "I'm just glad that everybody's going to get help."
He was outside working on his traps when his mother received a call from Champ telling her of the court victory.
"He said the case went through today, and all the kids in Canada on First Nations reserves have this help from the Jordan's principle case, to help kids on reserves that have disabilities," Meawasige said.
He added he was very proud of his mother for taking on the legal challenge and relieved to know help is on the way for his little brother.
"I believe (Jeremy) will be able to stay here."
His mother, meanwhile, was sleeping Friday afternoon after spending much of the night wide awake with jubilation.
The implications for First Nations children are also profound, said Cindy Blackstock, executive director of the First Nations Child and Family Caring Society of Canada.
She is fighting a separate case on First Nations child welfare in front of the Canadian Human Rights Tribunal, arguing that First Nations children have the right to welfare services on par with what provincial governments offer off-reserve children.
The Pictou Landing case, along with other recent court decisions, will eventually force Ottawa to improve welfare and health services for First Nations children.
"It's not lawful for the government of Canada to deny children services because of their race," Blackstock said in an interview.
"I think we can look forward to more judgments of this nature coming forward as Canadian courts say a child should be treated a child. You shouldn't be denying them services because of any kind of adult government issue, red tape."
Aboriginal Affairs Minister Bernard Valcourt did not immediately respond to the ruling.