The facility called Insite was promoted by its founders as a safe, humane space for drug abusers. The government said it abets drug abuse.

The top court issued its 9-0 unanimous decision in a case that has drawn international attention.

“The grave consequences that might result from a lapse in the current constitutional exemption for Insite cannot be ignored,” the court said.

Defenders of Insite — a taxpayer-funded operation in a seedy, drug-infested district of Vancouver, British Columbia — said the facility is a providing a form of health care which is a provincial matter under Canada’s constitution. The Canadian government countered that because heroin is a federally banned substance the national law should trump provincial rights.

The ruling said the government’s previous decision to end the drug-law exemption threatened injection drug users’ health and their lives.

“Insite has been proven to save lives with no discernible negative impact on the public safety and health objectives of Canada,” the court said.

Insite lawyer Joe Arvay said it means the facility can remain under a permanent exemption from Canada’s criminal drug laws. He said they lost on the jurisdictional issue but won on the right to continue with the exemption.

Other Canadians cities in the provinces of Ontario and Quebec have been looking at establishing similar sites but Arvay said the ruling applies only to the Vancouver facility.

“The battle for other sites across Canada remains to be fought,” he said, adding the ruling will give those cities hope. “Insite is going to remain open no matter what.”

Conservative Health Minister Leona Aglukak said in Parliament they will review the decision, but Arvay said there is no other avenue of appeal for the Canadian government.

The decision was greeted with a massive cheer from hundreds gathered outside Insite before dawn Friday.

As of 2009, there were 65 injection facilities in 27 cities in Canada, Australia, and western Europe, according to the Canadian Medical Association Journal. The World Health Organization has called them a “priority intervention” in slowing the spread of AIDS via infected needles.

Addicts are given clean needles and sterilized water in which to mix their drug. They bring their own drugs and inject at 12 stainless steel alcoves with mirrors on the walls so nurses on a raised platform can see them.

The storefront facility sits in the Downtown Eastside, 15 blocks of cheap rooming houses where addiction and street prostitution are rampant and an estimated 5,000 of the area’s 12,000 residents are believed to be addicted to drugs.

Julio Montaner, president of the International AIDS Society, said the area’s infection rate is the worst in the developed world. He said the decision “represents a victory for science over ideology.”

The Vancouver Coastal Health Authority Chief Medical Health Officer Patricia Daly said it means they can prevent life-threatening diseases in a vulnerable population.

Insite averages more than 800 visitors a day and has supervised more than a million injections since it opened in 2003. Insite has not reported any deaths at the facility.

When Insite opened, the Bush administration’s drug czar, John Walters, called the operation “state-sponsored suicide.” Canada’s Conservative government moved to close the site in 2008.