As the Conservative government's champion in the war on pot, Health Minister Rona Ambrose has taken some heavy blows and faces the prospect of more.

Ms. Ambrose was "outraged" in early June when the Supreme Court ruled that legal medical-marijuana users would be permitted to eat the drug as well as smoke it. She was "deeply disappointed" last week when Vancouver said it would regulate marijuana dispensaries, most of which obtain their supply from unauthorized sources.

Her government's efforts a year ago to end the right of medical-pot users to legally grow cannabis in their homes have been temporarily thwarted by a court challenge and could ultimately be struck down as a violation of civil rights.

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And, despite the Conservative government's vehement stand against pot, often wielded as a political club against Liberal Leader Justin Trudeau's stated support for legalization, Prime Minister Stephen Harper has presided over a period of increasing acceptance and normalization of marijuana in Canada.

Kirk Tousaw, the lawyer who successfully defended Victoria pot baker Owen Smith in challenging the prohibition on edible forms of the drug, recently filed submissions against the government's attempts to stop users from growing their own.

Four plaintiffs are asking that the government's Marijuana For Medical Purposes law be struck down as unconstitutional because the pot supplied by licensed producers is too expensive, and patients, they say, must choose between their "liberty" and their "health."

"I think that the Smith decision provides the federal court with a road map as to how the Supreme Court of Canada views medical-cannabis issues," Mr. Tousaw said in a telephone interview. "When the effect of a law is to harm already sick people, it's arbitrary and unconstitutional and patients are entitled to make reasonable medical choices and are entitled to have access to lawful forms of treatment under their physician's direction."

Mr. Tousaw and others argue that the government is losing the battle to tightly control medical marijuana because its approach was wrongheaded from the start, and that its own policies are largely responsible for the widespread emergence of the drug from the underground subculture. The government doesn't believe in marijuana as medicine, but, in its zeal to stop people from growing their own, it has licensed marijuana companies to be publicly traded, Mr. Tousaw said.

As a result, "Mr. Harper's government is responsible for essentially creating the largest and only federally sanctioned commercial regime for producing and selling medical cannabis on this continent, a regime that includes publicly traded companies now in the midst of merging and acquiring each other," he said. "So despite the Conservative government's real hatred for medical cannabis … you can now day-trade medical cannabis stocks on the Toronto Stock Exchange."

The use of cannabis for medical purposes, and recreationally, has gone way past the point of being normalized in Canada, Mr. Tousaw said. Repeated polls have suggested that, while access to marijuana may not be a priority for most Canadians, a majority want to see the law softened and a large number want the drug legalized.

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The government responds that it has an obligation to keep marijuana away from the vast majority of Canadian children who are not receiving it for medical purposes. While it doesn't want to deny a cancer patient access to a medicine that he or she believes to be beneficial, government officials point out that marijuana is not an approved drug in Canada.

"While Canadian courts have required the government to allow access to marijuana when authorized by a physician, the law is clear that this must be done in a controlled fashion to protect public health and safety," said a spokeswoman for Ms. Ambrose.

There is a fundamental difference, she said, between making medical marijuana available through licensed producers, who are approved by Health Canada and produce and distribute their product in a very controlled and secure fashion, and illegal storefronts that normalize the use of marijuana by having these stores in plain sight of families and children.

"This Conservative government wants to stop kids from smoking marijuana and we do not support making access to illegal drugs easier," she said. "Storefronts selling marijuana are illegal and will remain illegal under this Conservative government."

But they exist and are expanding in number.

The government had the opportunity to fully regulate medical-cannabis dispensaries, which repeatedly asked the government to make them lawful access points for patients, but it refused to do so, Mr. Tousaw said. At the same time, there was a void in supply and the dispensaries exist to fill that void. "So, in a way," he said, "the refusal of the government to regulate the dispensaries has produced the proliferation of dispensaries all across this country."

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But Rielle Capler, a researcher at the University of British Columbia who has studied medical-marijuana regulation, said the explosion in pot dispensaries coincided with the government's efforts in 2013 to rewrite the law to stop home-grown operations and replace them with licensed producers.

"There wasn't a smooth transition," Ms. Capler said. "A very small number of legally licensed producers were operating. A lot of them didn't have adequate supply. So there really was nowhere for patients to get a legal supply."

Meanwhile, the price of the legal pot was very high, she said. So many of the medical users who stopped growing their own turned to the dispensaries.

The government says there is no supply problem now that there are 25 licensed producers.

But the storefronts are unlikely to disappear any time soon. Jamie Shaw, the president of the Canadian Association of Medical Cannabis Dispensaries, said there are clear links between government policies and the rise of the unlicensed medical-marijuana industry.

"They created this whole home-grow model, then they tried to outlaw the home-grow model and created a new corporate model, but all of those models are running at the exact same time now," Ms. Shaw said.

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In the end, she argues, the dispensaries are beneficial for law enforcers, health authorities and patients.

"As long as you can trace a product back if they are having any problems, even if they are not following any standards or anything else, just having a place to say 'that's where I got it from' allows public officials to act on that and move to protect public safety," Ms. Shaw said. "By pushing all that back into the shadows, there's no ability to respond to that whatsoever."

It is certainly not what the government intended. Mr. Tousaw says the system of marijuana control, which still sees thousands of people arrested for possession every year, has been a failure.

"If the goal is to prevent access, it's not working," he said. "If the goal is to prevent people from participating in the black market, it's having the exact opposite consequence. If the goal is to enshrine a system where lots of Canadians have their future life prospects diminished because of arrest, well, it's doing that. And it's doing that unfortunately very well."