Posted Tuesday, February 07, 2012 by Mike Gibbons.
A patent application concludes with a series of patent claims. Analogous to the legal description that appears on a deed for a piece of property, the patent claims are where an inventor sets out a description of the intellectual property considered to be the invention. In short, the claims state the boundaries of the invention. One difference between the description of intellectual property in a patent and a description of real property in a title deed is that a patent will typically have a number of patent claims, whereas the title deed will usually have a single legal description of the real property.
Claims have a particular structure. An individual patent claim is a single sentence, beginning with a capitalized word and ending with a period. Punctuation is included in the claims to break them up into sections. The claims are numbered sequentially, beginning with claim 1.
An applicant for a patent provides a proposed set of claims with the application for the patent. In patent prosecution, during which time the inventor’s representative and patent office personnel work to finalize the scope of the patent, patent claims may be added, amended, canceled, combined, or otherwise modified. Such changes may alter the numbering of the claims from the initial list, but just prior to issuance the patent office will renumber the claims so that they begin with 1 even where the original first claim has been canceled during prosecution.
There are different types of patent claims. While they are each a single sentence and numbered sequentially, the claims themselves may relate to one another through the use of independent claims and dependent claims. An independent claim stands alone, completely describing a parcel of intellectual property. A dependent claim, however, refers to another claim and includes everything in that other claim.
For example, an independent claim may read “1. A motor vehicle comprising: a base; four wheels; and a frame for supporting a body.” A dependent claim could read “2. The motor vehicle of claim 1, wherein the body is black.” The effect of claim 2, depending on claim 1, is that it includes all of the subject matter in claim 1 plus everything disclosed by 2. Claim 2 does not stand alone. It depends upon claim 1, which is how it gets the name dependent claim.
An unusual type of claim is the “multiple dependent claim,” in which a dependent claim depends upon more than one other claim. Continuing the previous example, a multiple dependent claim might read “3. The motor vehicle of claims 1 or 2, wherein each of the four wheels is round.” The effect of this multiple dependent claim is that the inventor claims the subject matter of claims 1 and 3 and separately claims 1, 2 and 3.
Multiple dependent claims are not often used by skilled patent drafters. They add significant complexity for the patent examiner at the patent office. Consequently, the patent office charges a high surcharge for any multiple dependent claims. The high fee is usually enough encouragement not to include multiple dependent claims in a patent application. A single multiple dependent claim increases patent office filing fees for a patent application by more than 40%.