Canada is trying a radical approach to treating heroin addicts who prove to be resistant to other forms of treatment: let them have heroin.

Last month, Prime Minister Justin Trudeau’s government quietly enacted new rules that will let doctors prescribe pharmaceutical-grade heroin to treatment-resistant addicts, Alan Freeman reported for the Washington Post. The change will, specifically, allow the Crosstown clinic in Vancouver, Canada, to expand a program that lets heroin users go to the clinic — frequently multiple times a day — to safely inject pure heroin.

This isn’t an entirely new concept. It’s a type of program that’s widely known as heroin maintenance.

The idea, which has been tried in several European countries and Vancouver, is to allow some addicts to satisfy their drug dependency without a big risk of deadly overdose — since they’re supervised, with staff ready to use the overdose antidote naloxone should it be necessary — and without resorting to other crimes to obtain the drugs, such as robbery and burglary. And once users are in, they’re offered — or forced into — more standard rehabilitation programs, although some patients may go on using for life.

Researchers credit Switzerland’s program, the first national scheme of its kind, with reductions in drug-related crimes and improvements in social functioning, such as stabilized housing and employment. Canadian studies also deemed heroin maintenance effective for treating severe heroin addicts. A review of the research — which included randomized controlled trials from Switzerland, the Netherlands, Spain, Germany, Canada, and the UK — reached similar conclusions, in particular noting sharp drops in street heroin use among people in treatment.

One of the Canadian studies, the results of a randomized controlled trial published in the New England Journal of Medicine, put the promise of heroin maintenance treatment this way:

In this trial, both diacetylmorphine [heroin] treatment and optimized methadone maintenance treatment resulted in high retention and response rates. Methadone, provided according to best-practice guidelines, should remain the treatment of choice for the majority of patients. However, there will continue to be a subgroup of patients who will not benefit even from optimized methadone maintenance. Prescribed, supervised use of diacetylmorphine appears to be a safe and effective adjunctive treatment for this severely affected population of patients who would otherwise remain outside the health care system.

As the study notes, heroin maintenance treatment is typically allowed only as a last resort for heroin addicts after they try more traditional treatments. So it's not going to be possible for just anyone to casually stroll into a Canadian injection site and get a shot of heroin. According to the Post, the Canadian government expects the program to only be available “in cases where traditional options have been tried and proven ineffective.”

The idea is, as one can imagine, not without controversy. Trudeau’s Liberal Party has embraced a softer approach to drugs in general, even working to legalize marijuana. But Colin Carrie, a Conservative member of the Canadian Parliament and the party’s health policy spokesperson, told the Post his party remains opposed to the idea: “Our policy is to take heroin out of the hands of addicts and not put it in their arms.”

This is an argument you see a lot with other opioid maintenance treatments, such as methadone and buprenorphine. Both are opioids that tame people’s cravings for opioids like painkillers and heroin without producing, when taken as prescribed, the kind of euphoric high that painkillers and heroin do. Methadone and buprenorphine have decades of evidence of effectiveness behind them, and groups like the Centers for Disease Control and Prevention and the World Health Organization recommend them as treatments for opioid addicts.

Despite the evidence, judges have at times forced drug users to drop buprenorphine and methadone treatment to avoid jail time, because they see maintenance programs as simply “replacing one drug with another” instead of “getting clean.”

Sometimes “getting clean” just doesn’t work for addicts

But sometimes “getting clean” just doesn’t work for addicts. And although methadone and buprenorphine have proven very effective, in rare cases even those medicines may not work.

That presents a grim reality: A heroin addict continues using heroin purchased on the streets — that might be laced with who knows what — with potentially stolen money and maybe with a needle that carries an HIV or hepatitis infection. Or the user can inject in a facility that has relatively safe doses of heroin, clean needles, trained supervisors with an overdose antidote, and accessible treatment options.

No one will say that either of these options is perfect or even good. Heroin is still a very dangerous drug. The heroin maintenance programs reported an overdose rate of roughly one per 6,000 injections, according to a review of the research. None resulted in death, since staff could treat users with naloxone. The researchers said that the rate of overdoses is “well below the hazard from injecting street heroin,” but the overdoses show that heroin use always has risks.

Still, injection sites that provide pure heroin at least create the safest environment possible and reduce the most harm — even if they don’t vanquish the risk entirely. With America now embroiled in an opioid painkiller and heroin epidemic that kills tens of thousands a year, simply reducing harm with a program similar to the Canadian one could save a lot of lives.

Watch: The opioid painkiller and heroin epidemic, explained