In a 5-4 split, the Supreme Court held that the oncomouse and higher life forms in general are not patentable subject matter in Canada.

Harvard College researchers (the respondents) developed a process by which they could create transgenic animals whose genomes are altered by a cancer-promoting gene (called an activated oncogene).

"[14] The majority concluded that the oncomouse "must be considered to be the result of both ingenuity and the laws of nature"[15] and is an invention within the meaning of s.2 of the Patent Act, as it is both unobvious and a new and useful "composition of matter.

The sole question before the court was whether the words "manufacture" or "composition of matter," in the context of the Patent Act, are broad enough to encompass higher life forms such as the oncomouse.

"[22] The majority held that the words "manufacture" and "composition of matter" are not sufficiently broad to include a higher life form such as the oncomouse.

[26] The majority also referred to the Oxford English Dictionary definition of "composition" which is "a substance or preparation formed by combination or mixture of various ingredients" and concluded that the oncomouse cannot be understood in such terms.

[30] Justice Bastarache identified some of the serious issues surrounding the patentability of higher life forms including: the agricultural impact on farmers who wish to save and reuse seeds,[31] the rights of the "innocent bystander," who may come into possession of a patented organism by virtue of its ability to self-replicate and thus be subject to an infringement action,[32] deterrence of biomedical research and innovation,[33] and the potential for the commodification of human life, tissues and organs.

"[35] Although those are broad objectives, they determined that Parliament did not leave the definition of "invention" open and neither the language nor scheme of the Act suit higher life forms.

concurring, agreed with the reasoning of the Federal Court of Appeal and were of the opinion that the engineered oncomouse is an "extraordinary scientific achievement" and an inventive "composition of matter" within the meaning of s.2 of the Patent Act.

[45] He stated that Parliament could not have contemplated many other future inventions including genetically engineered lower life forms, moon rockets, antibiotics, telephones, e-mail or hand-held computers.

[50] Additionally, Binnie J. emphasized the fact that Parliament has repealed and avoided including provisions in the Patent Act dealing with the morality of inventions as an indication that these aspects of public policy should be dealt using other regulatory regimes.

[51] He identified the Assisted Human Reproduction Act[52] as an example of specialized legislated enacted to deal with public policy considerations similar to the ones at play in this case.

[53] Justice Binnie noted that the outcome of this case takes Canada on a very different trajectory than other countries, including the United States, Japan and Europe.

[55] The majority's reasoning in drawing the line between higher and lower life forms was called by Dan Burk a "rationally indefensible distinction.

"[56] Wendy Adams has found controversy in the court's belief in ethical neutrality in relation to animal welfare under the Canadian patent system.