The Rosetta Stone for the Doctrine of Means-Plus-Function Patent Claims (1997)

I. INTRODUCTION A patent grants to inventors `the right to exclude others from making, using, offering for sale, selling, or importing the patented invention' in exchange for full disclosure of the invention.(1) The patent must contain a complete description of the invention in sufficient detail so that a person skilled in the art to which the invention pertains can practice the invention.(2) The patent must conclude with one or more claims which particularly point out and distinctly claim the subject matter that the patentee regards as the invention.(3) The claim measures the scope of the patent grant.(4) Patent in fringement generally is established if the elements or limitations of the claim are found in an accused device, or, in other words, if the claim the accused device.(5) A claim is invalid or unpatentable if it is overbroad, indefinite, or if it covers the prior art. For over a century, inventors have been required to specify with particularity the claimed invention so that the inventor might be secured all of which she is entitled, the public might be apprised of what conduct is prohibited during the patent term, and the invention might be defined for purposes of determining whether it is patentable.(6) Federal patent power derives from the United States Constitution which authorizes Congress [t]o promote the Progress of Science and useful Arts by securing for limited Times to ... Inventors the exclusive Right to their respective Discoveries.(7) Since 1790, Congress has exercised this power and has periodically enacted and amended various patent statutes.(8) The last major revision of the patent statutes, and also the first major revision since 1870, is the 1952 Patent Act which introduced into law Title 35 of the United States Code.(9) The Act's acclaimed purpose was to revise and codify the existing laws relating to patents and the Patent Office.(10) The 1952 Patent Act appended as the last paragraph of section 112 new language relating to functional claims, i.e., claims that define an invention in terms of what it does rather than in terms of what it is. Unmodified since it was first enacted, this paragraph provides: An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material r or acts described in the specification and equivalents thereof.(11) The first clause permits a patent applicant to express an element in a combination claim in terms of what it does rather than in terms of its structure.(12) The second, or scope clause, defines the scope of means-plus-function language and specifies the breadth of protection otherwise permitted by the first clause.(13) In the specification, the applicant must disclose the structure, materials, or acts that perform the claimed function; the means-plus-function limitation in the specification must be construed to cover the structure, material, or acts and their equivalents.(14) Thus, while general claims enjoy a scope as broad as their unambiguous claim language permits, means-plus-function claims are given a different, more limited treatment.(15) Combination claims with elements described in terms of what they do have long been recognized as apt.(16) Such claims provide an inventor with flexibility to claim what she regards as the invention. Terms that define what the element does may provide a way to claim the invention in cases where structural terms are unnecessarily cumbersome or inadequate. Also, the broad coverage afforded by functional terms allows the courts to resolve infringement issues without extending patent protection beyond the scope of the literal claim.(17) Section 112, last paragraph, provides a vehicle for such claims and for the realization of these benefits. …