Update: The legislation was officially overturned on Sept. 7, 2016.

Health Canada has moved to allow doctors to apply for special access to prescribe pharmaceutical-grade heroin to severe addicts, which would overturn a ban imposed by the previous Conservative government.

The federal department said in a statement issued on Friday that a "significant body of evidence" supports the medical use of diacetylmorphine, also known as pharmaceutical-grade heroin.

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"Diacetylmorphine is permitted in a number of other jurisdictions, such as Germany, the Netherlands, Denmark, and Switzerland, to support a small percentage of patients who have not responded to other treatment options, such as methadone and buprenorphine," the statement said.

Liberal Health Minister Jane Philpott, a doctor, has emphasized that her government will take an evidence-based approach to drug policy. In January, Dr. Philpott toured and gave a stamp of approval to Insite, Vancouver's supervised injection site – which the Conservative government had fought all the way to Supreme Court.

Doctors in Vancouver drew attention to the issue of prescription heroin three years ago after clinical trials found that, for a few entrenched addicts who had failed repeatedly with more traditional treatments, prescription heroin administered in a supervised, medical setting is safe and effective.

Those receiving prescription heroin experienced physical and mental-health improvements, were more likely to stay in treatment and reduce illegal drug use and criminal activity than those on methadone.

As people began completing the clinical trials, doctors applied for, and received, special permission under Health Canada's Special Access Programme (SAP) to continue prescribing the drug to them. The SAP allows doctors access to non-marketed or otherwise unapproved drugs for patients with serious or life-threatening conditions.

Health Canada approved the applications in September, 2013.

Rona Ambrose, then Conservative health minister, introduced new regulations to ban doctors from prescribing "dangerous drugs" such as heroin, cocaine and LSD. The trial participants launched a constitutional challenge and continued to receive prescription heroin under an interlocutory injunction.

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Under Health Canada's planned change, heroin would once again be allowed under the SAP; other drugs, such as cocaine, will be accessible only for research.

The reversal comes as B.C. fights an uphill battle against illicit drug overdose deaths, fueled in large part by illicit fentanyl. In the first four months of 2016, the province has recorded an 88 per cent increase in illicit drug overdose deaths compared to the same period last year. Fentanyl – a powerful synthetic opioid – has been detected in half of those deaths.

Scott MacDonald, physician lead at the clinic that ran the trials, called Health Canada's plan a welcome step, but said access to prescription heroin should be improved even further. Narcotics Control Regulations mean it can still takes many months, and an onerous application process, to get the drug for patients.

"This is not the total solution, but it's part of the solution," he said Friday. "We need intensive treatments like this urgently."

Lee Wheeler, who was part of the clinical trial and is one of 100 people receiving prescription heroin in Vancouver, credits the program with saving his life.

"I don't have to worry about the dope on the street, the overdoses and all this stuff," he said. "I think it's really bad what's going on with the people overdosing.

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"I have nothing but good things to say about [prescription heroin]. I'd like to see more people get on to it, to get them out of the ruts they're in."

The plan will now undergo a 30-day consultation period.