There are two basic types of claims: • the
independent claims, which stand on their own, and • the
dependent claims, which depend on a single claim or on several claims and generally express particular embodiments as fall-back positions. 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, narrower than the independent claim upon which it depends. Although this results in coverage narrower 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: :* Clarification/broadening of the independent claim: Independent claims are typically written with broad terms, to avoid permitting competitors to circumvent the claim by altering some aspect of the basic design. But when a broad wording is used, it may raise a question as to the scope of the term itself. If a dependent claim is specifically drawn to a narrower interpretation, then, at least in the U.S., the doctrine of claim differentiation states that the scope of the independent claim is strongly
presumed be different from, and therefore broader than, the scope of the dependent claim. The doctrine dictates that it "is improper for courts to read into an independent claim a limitation explicitly set forth in another claim." This means that if an independent claim recites a chair with a plurality of legs, and a dependent claim depending from the independent recites a chair with four legs, the independent claim is not limited to what is recited in the dependent claim. The dependent claim protects chairs with four legs, and the independent claim protects chairs with four legs as well as chairs having two, three, five or more legs. Similarly, it may be unclear whether a "base" includes a "set of legs." A dependent claim, including the phrase, "wherein said base comprises a set of legs," if allowed by the
patent examiner, clarifies that the word "base" in the independent claim does not necessarily include legs. In practice, dependent claims are often used to home in on the inventor's preferred embodiment of the invention (e.g., the actual product design that the inventor intends to use.) The independent claim broadly describes the invention; dependent claim #1 describes the invention in a narrower aspect that more specifically describes the preferred embodiment; dependent claim #2 is narrower still; etc. :* Possible invalidity of independent claim: It is impossible to know, when beginning the application process and even at the time of patent issuance, if a patent claim is valid. This is because any publication dated before the application's
priority date and published anywhere in any language can invalidate the claim (excluding publications by the inventor published during the grace period in certain countries such as U.S., Canada and Japan). Furthermore, even applications that were not yet published at the time of filing, but have a priority date prior to the priority date of the application, can also invalidate the claim. As it is impossible to gain an absolute and complete knowledge of every publication on earth, not to mention unpublished patent applications, there is always some degree of uncertainty. If the independent claim is determined to be invalid, however, a dependent claim may nevertheless survive, and may still be broad enough to bar competitors from valuable commercial territory. 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 • a physical entity, i.e. a product (or material) or an apparatus (or device, system, article, ...). The claim is then called respectively "
product claim" or "
apparatus claim"; or • an activity, i.e. a process (or method) or a use. The claim is then called respectively "
process claim" (or
method claim) or "
use claim". In the United States, these categories are referred to as the four statutory categories of invention, and they are:
processes,
machines,
manufactures, and
compositions of matter. Notably, printed matter (including data stored on a
computer drive) and signals (such as transient electromagnetic waves, (see
in Re Nujten).) do not belong to any of the four statutory categories and are not patentable in US. However, such signals are considered patentable by the
European Patent Office (EPO). The "process" claims have been the most controversial, particularly in cases, when processes involve transformations of non-statutory (and/or non-physical) entities, such as data into data, or electronic money exchange. Three
US Supreme Court justices (
Sonia Sotomayor,
Ruth Bader Ginsburg, and
Stephen Breyer) in their concurring opinion in
Alice Corp. v. CLS Bank International suggested, that all business methods should be excluded from patentability: "[A]ny claim that merely describes a method of doing business does not qualify as a process under § 101." However, the
SCOTUS refused to accept this position so far, and some business method patent claims are possible in the US, although the
case law in the area is still evolving (see
Software patents under United States patent law).
Special types of claims In addition to aforementioned four statutory categories of claims, there are also many other "flavours" of claims, 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. == Interpretation or claim construction ==