In Canadian patent law, only “inventions” are patentable. Under the Patent Act, only certain categories of things may be considered and defined as inventions. Therefore, if a patent discloses an item that fulfills the requirements of novelty, non-obviousness and utility, it may nonetheless be found invalid on the grounds that it does not fall within one of the statutory categories of “invention”. Since the Patent Act, the categories of patentable subject matter have been defined and interpreted by Canadian courts. Definition and categories of invention Section 2 of the Patent Act defines “invention” as: [A]ny new and useful art, process, machine, manufacture or composition of matter, or any new and useful improvement in any art, process, machine, manufacture or composition of matter. Each of the five categories of inventions has been further defined by the Canadian Intellectual Property Office and the Canadian courts. Art Shell Oil Co. v. Commissioner of Patents defined the term “art” broadly as the application of knowledge to effect a desired result. A narrower interpretation of the term was offered by Lawson v. Canada (Commissioner of Patents): An art or operation is an act or series of acts performed by some physical agent upon some physical object and producing in such object some change either of character or of condition. Process A process is the application of a method to a material or materials. The process may be patentable even if the process does not produce a patentable product. In Tennessee Eastman Co. v. Commissioner of Patents, the Supreme Court of Canada concluded that medical or therapeutic methods are not contemplated in the definition of invention as a kind of process. Machine The Canadian Intellectual Property Office's Manual of Patent Office Practice has defined a machine as the mechanical embodiment of any function or mode of operation designed to accomplish a particular effect. Manufacture Manufacture implies a product made by hand, by machine, industrially, by mass production and so forth, by changing the character or condition of material objects. Harvard College v. Canada (Commissioner of Patents), as discussed below, has held that higher life forms, such as genetically altered mice, do not fall within the meaning of manufacture. Composition of matter “Composition of matter” is defined as a combination of ingredients or substances – a solid, gas, or fluid – as a chemical union or a physical mixture. This definition has been taken to include enzymes,