In United States patent law
, a composition of matter
is one of the four principal categories of things that may be patented. The other three are a process (also termed a method), a machine
, and an article of manufacture. In United States patent law, that same terminology has been in use since the first patent act in 1790 (with the exception that processes were formerly termed "arts").
The United States Supreme Court has defined "composition of matter" to mean "all compositions of two or more substances and all composite articles, whether they be the results of chemical union, or of mechanical
mixture, or whether they be gases, fluids, powders or solids." That definition is problematic, however, because composite articles can be articles of manufacture—as in the case of a piece of plywood, a concrete sidewalk, a road, a fibreglass bathtub, a (kitchen) countertop, or a flitch beam.
Robinson on Patents
has defined "composition of matter" in these terms:
A composition of matter is an instrument formed by the intermixture of two or more ingredients, and possessing properties which belong to none of these ingredients in their separate state. ...The intermixture of ingredients in a composition of matter may be produced by mechanical or chemical operations, and its result may be a compound substance resolvable into its constituent
elements by mechanical processes, or a new substance which can be destroyed only by chemical analysis.
A newly synthesized chemical compound or molecule may be patented as a composition of matter. Patents have been allowed on transitory products, such as short-lived chemical intermediates.