The rule is well-intentioned. After all, it seems unfair that Canadians pay less for many name-brand prescription drugs than do Americans.

But the Trump administration’s drug importation plan won’t meaningfully reduce Americans’ bills at the pharmacy. Further, it could endanger their health — and the health of Canadians.

Canada can’t serve as America’s medicine cabinet; it’s simply too small. Our northern neighbor has barely one-tenth as many people as the United States.

Further, Canada doesn’t have enough drugs to meet the needs of its own citizens. Many of the most cutting-edge drugs are in short supply in Canada, if they’re available at all. One analysis of more than 240 new medicines brought to market between 2011 and 2018 found that less than half were available north of the border. Nearly 88 percent were available in the United States.

Roughly four in 10 Canadian households have struggled to fill prescriptions due to shortages, according to the Angus Reid Institute. The country’s health system faces shortfalls of about 2,000 drugs.

If Americans sourced just 20 percent of their prescriptions from Canada, our northern neighbor would run out of medicines in just six months, according to research from the University of Texas.

Canadian officials would not let that happen. They would prohibit their pharmacies and wholesalers from exporting drugs. Already, Prime Minister Justin Trudeau’s government has panned drug importation, warning the Trump administration that “Canada does not support actions that could adversely affect the supply of prescription drugs in Canada.”

Drug companies also wouldn’t cooperate with the administration’s importation plans. They’d sell just enough pills in Canada to meet local demand — not so many that firms could export large quantities to the United States.

Even if importation were logistically feasible, it still wouldn’t save Americans as much money as its proponents promise.

Consider the story of a 74-year-old Michigan man with type 1 diabetes who recently ventured north after hearing about Canada’s supposedly cheaper insulin prices. As the Detroit Free Press reported, he was dismayed to find that his prescription was more expensive out-of-pocket in Canada than it would have been at his local American pharmacy, where he could use his insurance card.

His experience is hardly unique. Canadian pharmacists have noted that “the flow of cross-border patients (has) slowed considerably” in recent years, as more and more Americans realize that filling prescriptions at their local pharmacies is often cheaper than heading north.