The Supreme Court of Canada ruled in the federal government's favour on Friday in two cases which sought to force Ottawa to help foot the bills for smokers who get sick.
The court unanimously sided with the federal government in both.
"It is plain and obvious that the tobacco companies' claims against Canada have no reasonable chance of success and should be struck out," the justices' concluded in the ruling.
One case involved a class-action suit against Imperial Tobacco by smokers who said they were tricked into thinking so-called mild or light cigarettes were less harmful than regular smokes.
They want Imperial to repay what they spent on the cigarettes, as well as compensation for damages.
The other concerned a lawsuit by the British Columbia government against tobacco companies to recoup billions of provincial health-care dollars spent on treating smoking-related diseases.
The B.C. government argued that the tobacco companies knew by 1950 that smoking was harmful to peoples' health and did not adequately warn them.
In both cases, the tobacco companies tried to get the federal government to share the liability and to help pay any costs if they were found liable.
Imperial Tobacco said Health Canada initially opposed warning labels on cigarettes, but then changed its policy in 1967 and advised smokers to switch to light or mild brands because they were less harmful.
The company also said the federal Agriculture Department researched and manufactured low-tar tobacco and collected royalties on sales of light and mild cigarettes.
The two cases have been working their way up the judicial ladder for years.
The tobacco companies tried to get Ottawa added as a third-party defendant in a case brought against them by the government of British Columbia. The B.C. Supreme Court rejected their argument.
But in December 2009, the provincial appeals court, in a 3-2 decision, overturned that ruling after accepting the companies' argument that the federal government had a role in designing some tobacco strains and warning people about the risks of smoking.
The Supreme Court's ruling on Friday overturned that split decision by the appeals court.
Not surprisingly, Imperial Tobacco wasn't happy with the ruling.
"Obviously, we're disappointed that the Supreme Court of Canada has decided to let the government of Canada off the hook in its involvement in the tobacco industry," company spokesman Eric Gagnon told The Canadian Press.
A statement from Health Minister Leona Aglukkaq's office welcomed the ruling:
"The government of Canada is pleased with today's Supreme Court of Canada decision. The court's unanimous decision makes it clear that Canadian taxpayers will not be liable for the claims made against tobacco companies."
Along with B.C., three other provinces — Ontario, New Brunswick, Newfoundland and Labrador — are suing the tobacco companies. Nova Scotia, Manitoba, Quebec and Alberta have also announced their intention to pursue lawsuits.
Rob Cunningham of the Canadian Cancer Society urged provinces to go after the tobacco companies.
"There is national momentum and we have to ensure that the outcome at the end of the day is in the interest of public health," he said.