Martha Hall Findlay, the former Liberal member of Parliament, has done the cause of clear thinking a favour by challenging one of the sacred cows of Canadian politics: the protectionist system that keeps the price of milk, eggs and poultry in this country much higher than it needs to be.

So-called supply management is a subject guaranteed to make eyes glaze over and politicians run for cover. But the fact is it forces Canadian consumers to pay hundreds of dollars a year to subsidize a dwindling number of protected farmers, and penalizes other farmers by undermining Canada’s efforts to expand trade in agriculture. The system is long past its sell-by date.

Hall Findlay, a past and possibly future contender for the Liberal leadership, blew the whistle on supply management last week in a research paper pointing out the cost to ordinary families. A family that buys four litres of milk a week, she concluded, pays $300 more a year than it would in the United States. Even worse, low-income people bear a disproportionate share of the cost of keeping milk, egg and poultry prices as much as 300 per cent higher than market levels. Simply put, they spend a bigger share of their income on food.

Hall Findlay is also challenging the conventional political wisdom that the system can’t be changed because of the electoral clout of protected farmers. She argues there are only 13 ridings with more than 300 dairy farmers, and even in those areas more farmers stand to gain from expanding agricultural exports.

Still, all three federal parties support supply management. The Liberals, in particular, rushed to the system’s defence last week when the Conservative government moved to enter the talks for a new Trans-Pacific trade agreement. Absurdly, they argued it guarantees food safety — as if Canadians were at mortal risk from the hundreds of other imported agricultural products not covered by the system.

Defenders argue that without supply management, Canadian dairy farmers would be crushed by American corporate exporters. They also suggest it would be unfair to devalue the significant investments farmers have made in quotas. But, as Hall Findlay points out, Australia dismantled a very similar system in 2001 and effectively managed these problems.

Canada will come under pressure to ditch supply management as it goes ahead with the Pacific trade talks. But change should come not as a concession to foreigners, but as a sound policy move made in the interests of Canadian consumers.