A controversial mouse, genetically modified to make it better suited for cancer research, may not be patented under current Canadian law, the country's top court ruled Thursday.

Researchers at Harvard University developed the mouse in the early 1980s. It's predisposed to cancer, which facilitates clinical research.

The Harvard Mouse, also called the Oncomouse, has been patented in the United States, much of Europe and Japan for more than a decade.

In a 5-4 judgment, the court said the mouse does not qualify as an invention under the federal Patent Act of 1869.

"The act in its current form fails to address many of the unique concerns that are raised by the patenting of higher life forms," wrote Justice Michel Bastarache in the majority decision.

Harvard researchers wanted the high court to allow them to patent the process used to alter the mice, as well as the mouse itself and any of the rodents' offspring that may inherit the modified gene.

The SCC ruled the mouse itself cannot be patented, but the biochemical process used to modify it may be. The court added that the ruling may disadvantage Canada's biotechnology industry, but Parliament could amend the 19th century Patent Act.

"It creates a hole or a gap in our patent coverage compared to our major trading partners," said Harvard lawyer David Morrow.

BIOTECanada, which represents biotechnology researchers and companies said Thursday the decision is bad news. It said the ruling would see top biotech researchers leave the country because they wouldn't have protection for their ideas.

Church and environmental groups had intervened in the high court case, arguing Parliament - not the courts - should make the morally and ethically sensitive decision.

Environmentalists welcomed the ruling. "Life forms are not light bulbs, and mammals are not machines," said Joanne Dufay of Greenpeace Canada. "This is a victory for life."

In countries were the mouse is patented, anyone wishing to use it for research has to pay a licence fee to Harvard until the patent expires.

Some believe the Harvard Mouse needs to be patented to encourage scientific research and protect intellectual property.

But others think it is unethical to commercialize multicellular life or to patent life forms for commercial profit.

Canada has allowed genetically modified crops and single-celled organisms such as bacteria and yeast to be patented.