OTTAWA—A group of Canadian lawmakers is teeing off at what the country's golfers say is a decades-old unfair rule in the country's tax law.

Since 1971, Canadians have been barred from deducting greens fees for business-related golf outings. Canadian companies and businessmen can deduct hockey and other professional sports events, theater and concert tickets, and pricey meals at the country's finest restaurants, so long as they are business-related. But deducting a host of golf-related expenses—a staple of the tax code south of the border in the U.S.—is out of bounds.

A caucus of about two dozen parliamentarians from across all political stripes is pushing to persuade Canadian Finance Minister Jim Flaherty, himself an occasional golfer, to throw out the old law—introduced in an era when policy makers still viewed golf as an elitist pursuit. Today, golf is the country's most popular recreational activity, beating out even the national pastime of hockey, according to the country's statistics agency.

"It seems to me times have changed, and there's a chance to revisit this," said Russ Hiebert, a member of the ruling Conservative party. He represents an area south of Vancouver that is home to eight golf courses and a driving range.

Peter Stoffer, a member of the left-leaning opposition New Democratic Party, agrees. He says golf is environmentally friendly; it's a game that's often used to help raise cash for charity; and it promotes a healthy lifestyle among Canada's youth. His district, near Halifax, is home to seven golf courses.