Means-plus-function claims (and new developments in patentability of pure algorithms)

Every patent document has two major sections. The first section, called the specification, is primarily a technical document intended to describe the invention in sufficient detail such that a person of ordinary skill in the art can make and use the invention in the best mode contemplated by the inventor. The second section is primarily a legal document and contains the claims. A patent gives the inventor a time-limited monopoly in the invention. The claims provide the legal description of that monopoly. When an inventor asserts a patent against an alleged infringer, the claims determine whether an infringement has occurred. Three types of claims are commonly used for electrical engineering-type inventions. These three types are: apparatus claims, method claims, and means-plus-function claims. Means-plus-function claims are a special type of apparatus claims. In means-plus-function claims, the physical elements of the apparatus are described in the claim by reciting the functional aspects of the elements but not the structural aspects.