OTTAWA - The Supreme Court of Canada won't stand in the way of a proposed multibillion-dollar class-action lawsuit on behalf of some 100,000 cattle farmers hurt by the 2003 mad cow scare.

The high court declined Thursday to hear an appeal by the federal government and Winnipeg-based feed company Ridley Canada, who sought to derail the lawsuit.

As is usual, the top court provided no reasons for turning down the appeal application.

At issue is whether farmers who suffered economic losses as a result of the 2003 border closure over BSE-contaminated cattle could sue for what they argue was negligent regulatory policy.

The Ontario Court of Appeal last year cleared the way for much of the protracted lawsuit to proceed to the next step, which will determine whether the case can be classified as a class action.

Co-ordinated suits from producers in Alberta, Saskatchewan, Ontario and Quebec are seeking at least $7 billion in losses and another $100 million in punitive damages.

Cattle farmer Bill Sauer, the lead plaintiff in Ontario, has argued that Ottawa introduced regulations in 1990 that specifically allowed the feeding of cattle parts to other cattle.

That's the way bovine spongiform encephalopathy, or mad cow disease, is spread.

The Canadian regulations came in a full two years after Britain had banned the practice, and three years after Canada barred uncertified cattle imports from the United Kingdom because of BSE fears.

The Canadian government didn't ban the dangerous feed practices until 1997.

The lawsuit now proceeds -- even as a new round of criticisms is being levelled at Ottawa over the Conservative government's latest policy shift on mad cow prevention and detection.

A scientist at the Canadian Food Inspection Agency was fired this month after stumbling upon a classified policy document that shows the government decided last year to cut back on inspections of meat, meat products, animal feed and commercial seeds, among other food items.

The cost-cutting plan, which came from the office of Agriculture Minister Gerry Ritz and was approved by Treasury Board last November, has not yet been made public.

But leaked copies indicate the Harper government is holding off on a public announcement of the plan "owing to significant communications risks.''

The Professional Institute of the Public Service of Canada, the union representing the fired scientist, says the new inspection policy "will amplify risk management and the risk will be to the health of Canadians.''

Liberal MPs issued a news release this week demanding the Conservatives release the full policy document at once.

"Even with the little we know about it, it is clear that this plan will hurt farmers and threatens the food we all eat,'' said Liberal agriculture critic Wayne Easter.

But a spokesman for the Canadian Food Inspection Agency said Canada is simply moving toward a system used elsewhere in the world.

Freeman Libby, national director for the CFIA's strategic projects team, said cost-saving is not the driving factor.

"Basically we're asking plants to have good quality control in place and we'll come in and audit their ability to be in compliance,'' Freeman said in an interview. "It's preventative-type measures versus reactive.''