Patent claim

In a patent or patent application, the claims define, in technical terms, the extent, i.e. the scope, of the protection conferred by a patent, or the protection sought in a patent application. In other words, the purpose of the claims is to define which subject-matter is protected by the patent (or sought to be protected by the patent application). This is termed as the "notice function" of a patent claim—to warn others of what they must not do if they are to avoid infringement liability. The claims are of the utmost importance both during prosecution and litigation alike.
For instance, a claim could read:
Background.
In most jurisdictions, a patent is a right to exclude others from making, using, importing, selling or offering for sale the subject matter defined by the claims when the claim is for a thing (apparatus, composition of matter, system, etc.). If a claim is for a method, the right to exclude would be to exclude any single party from carrying out all the steps of the claim. In order to exclude someone from using a patented invention, the patent owner, or patentee, needs to demonstrate in a court proceeding that what the other person is using falls within the scope of a claim of the patent; therefore, it is more valuable to obtain claims that include the minimal set of limitations that differentiate an invention over what came before ("i.e.," the so-called prior art). But the fewer the limitations in a claim, the more likely it is that the claim will cover, or "read on," what came before and be rejected during examination or found to be invalid at a later time for obviousness or lack of novelty.
History.
Patents have not always contained claims. In many European countries, patents did not contain claims until the 1970s. Before that time, it was often difficult to decide whether a product infringed a patent, since the sole basis to know the extent of protection was the description, in view of the prior art. Claims have been necessary parts of U.S. patent applications since the enactment of the Patent Act of 1836.
However, even among patent legal systems in which the claims are used as the reference to decide the scope of protection conferred by a patent, the way the claims are used may vary substantially. Traditionally, two types of claiming systems exist:
No patent system today is a purely either "central" or "peripheral", but the system used in Germany and most of the other countries of continental Europe is considered more central than the system currently used in the United Kingdom, the United States, and especially Japan, which are more peripheral. In recent years, Japan's system has become more peripheral, while the system used in the United States was becoming more central because of the increasing resort in US patent litigation to the doctrine of equivalents to expand claim scope unpredictably, until the US Supreme Court reversed that trend in the "Warner-Jenkinson" case in 1997.
Requirements and structure.
In most modern patent laws, patent applications must have at least one claim, which are critical defining elements of the patent and the primary subject of examination. In some patent laws however, a date of filing may be obtained for an application which does not contain any claim.
European Patent Convention.
Under the European Patent Convention (EPC), a claim must define the matter for which the protection is sought in terms of technical features. These technical features can be either structural (e.g. a nail, a rivet) or functional (e.g. fastening means).
Regarding the structure of a claim, under the EPC, what is called the "preamble" is different from the meaning the "preamble" has under U.S. patent law. In an independent claim in Europe, the preamble is everything which precedes the expression "characterized in that" or "characterized by" in a claim written according to the so-called "two-part form", and therefore everything which is regarded as known in combination within one prior art document, namely the closest prior art document. For this reason, in Europe, the preamble of a claim is sometimes also called "pre-characterizing portion".
United States.
A claim may include the following parts:
Interpretation or claim construction.
The claims often use precise language. Certain words commonly used in claims have specific legal meanings determined by one or more court decisions. These meanings may be different from common usage. For instance, the word "comprises", when used in the claims of a United States patent, means "consists at least of". By contrast, the word "consists" means "consists only of", which will lead to a very different scope of protection.
Furthermore, in U.S. patent practice at least, inventors may "act as their own lexicographer" in a patent application. That means that an inventor may give a common word or phrase a meaning that is very specific and different from the normal definition of said word or phrase. Thus a claim must be interpreted in light of the definitions provided in the specification of a patent. The specification of a patent is a written description of how to make and use the invention (see also: sufficiency of disclosure). In U.S. law, a claim is given its broadest reasonable interpretation consistent with the specification during prosecution of the application; however, in a suit for patent infringement, a claim is interpreted in a Markman hearing.
Basic types and categories.
There are two basic types of claims:
The expressions "in one embodiment", "in a preferred embodiment", "in a particular embodiment", "in an advantageous embodiment" or the like often appear in the description of patent applications and are used to introduce a particular implementation or method of carrying out the invention. These various embodiments may or may not each be claimed with specificity. They might serve as multiple examples of a more general "genus" that is claimed. In some cases the examiner might declare that what the applicant presented as variations of one invention are actually separate inventions that need to be examined individually.
An independent ("stand alone") claim does not refer to an earlier claim, whereas a dependent claim does refer to an earlier claim, assumes all of the limitations of that claim and then adds restrictions (e.g. "The handle of claim 2, wherein it is hinged.") Each dependent claim is, by law, more narrow than the independent claim upon which it depends. Although this results in coverage more narrow than provided by the independent claim upon which the second claim depends, it is additional coverage, and there are many advantages to the patent applicant in submitting and obtaining a full suite of dependent claims:
Under the European Patent Convention, when a claim in one particular category (see below), e.g. a process claim, depends on a claim from a different category, e.g. a product claim, it is not considered to be a dependent claim but an independent claim. Under U.S. law, this is still counted as a dependent claim, regardless of the class change.
The rules of claim drafting also permit "multiple dependent claims" that reference more than one other claim, e.g.: "3. Method of claim 1 or 2, further comprising..." The rules for this are quite specific: specific claims must be referenced ("the method of any of these other claims" is incorrect); the claims must be referenced in the alternative ("the method of claims 1 and 2" is incorrect); etc. While still acceptable, this claim style is seldom used in the U.S. because it is counted for filing fee purposes according to the number of claims that it references. Thus, if the claim depends from three former claims, it is counted for fee purposes as three dependent claims. In light of the "excess claim" fees currently imposed by the USPTO, this tactic can quickly become expensive. Multiple dependent claims are, however, very commonly used in other jurisdictions, including Europe.
Claims can also be classified in categories, i.e. in terms of what they "claim". A claim can refer to
Special types of claims.
In addition to the above basic claim types, there are also many special types of claim which are used in different circumstances. Sometimes a particular claim form is required by law if a patent is to be granted for a particular invention, such as for a second medical use of a known substance where the "Swiss-type" claim might be required. Another reason to use a particular claim might be to catch a particular class of infringer.