TORONTO - Federal regulations that bar Canada's generic drug makers from copying brand-name products for eight years after patents expire will come under the judicial microscope Tuesday as a two-year-old lawsuit reaches Federal Court.

The generic drug makers want the court to set aside rules that they argue cost consumers $115 million in extra drug costs every year.

The regulations, implemented in 2006 under the Food and Drugs Act, were designed to protect the extensive and expensive data that manufacturers need to seek approval for a drug. The data include the results of studies and clinical trials.

The rules prohibit Health Canada from licensing a generic version -- generally cheaper than the brand-name equivalent -- until after the eight-year period for those drugs where patent-protections have lapsed.

The "data exclusivity" is extended for a further six months if pediatric trials were involved in the development.

The generics argue that's simply too long.

"Basically, it's just a ban on competition," said Jeff Connell, a spokesman for the Canadian Generic Pharmaceutical Association.

"It's got nothing to do with data. It's all about market exclusivity."

The generics argue the North American Free Trade Agreement only affords a maximum of five years protection for the research-based drug makers.

They claim the government exceeded its authority in proclaiming regulations they called a "kick in the shins" because they go well beyond what's called for in the trade deal.

"We're asking the court to rule them unlawful and have them thrown out," said Connell.

The federal government said the changes were designed to clarify the rules and cut litigation costs.

The generics point to lower-cost equivalents of popular medicines such as the anti-depressants Zoloft and Wellbutrin, or Pravachol, a drug that lowers cholesterol, as examples of medications that would not have been readily available to consumers had the rules been in place before 2006.

The companies that develop prescription drugs in Canada have said the European Union protects brand names for 10 years, so Canada is not out of line.

Generics typically cost half or less than the original.

Latest data from IMS Health, an organization that provides global market intelligence to the pharmaceutical and health-care sectors, indicate generic drugs are now dispensed in just over half of all prescriptions in Canada. At the same time, they account for 22.5 per cent of the roughly $20 billion Canadians spend on prescription drugs.

Brand-name drugs enjoy 20 years of patent protection, but their manufacturers argue patents lapse or can be challenged in court.

The suit has been tied up in pre-trial wrangling since it was launched two years ago.