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Claim (patent)

Claim (patent)

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Patent claims are the part of a patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 or patent application
Patent application
A patent application is a request pending at a patent office for the grant of a patent for the invention described and claimed by that application. An application consists of a description of the invention , together with official forms and correspondence relating to the application...

 that defines the scope of protection granted by the patent. The claims define, in technical terms, the extent of the protection conferred by a patent, or the protection sought in a patent application. The claims are of the utmost importance both during prosecution
Patent prosecution
Patent prosecution describes the interaction between applicants and their representatives, and a patent office with regard to a patent, or an application for a patent...

 and litigation
A lawsuit or "suit in law" is a civil action brought in a court of law in which a plaintiff, a party who claims to have incurred loss as a result of a defendant's actions, demands a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint...


For instance, a claim could read:
  • "An apparatus for catching mice, said apparatus comprising a base for placement on a surface
    In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball...

    , a spring member..."
  • "A chemical composition for cleaning windows, said composition comprising 10–15% ammonia, ..."
  • "Method for computing future life expectancies, said method comprising gathering data including X, Y, Z, ..."

A patent is a right to exclude others from making, using, selling or offering for sale the subject matter defined by the claims. In order to exclude someone from using a patented invention in a court, the patent owner, or patentee, needs to demonstrate 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
Prior art
Prior art , in most systems of patent law, constitutes all information that has been made available to the public in any form before a given date that might be relevant to a patent's claims of originality...

. On the other hand, 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 lack of novelty
Novelty (patent)
Novelty is a patentability requirement. An invention is not patentable if the claimed subject matter was disclosed before the date of filing, or before the date of priority if a priority is claimed, of the patent application....



Patents have not always contained claims. In many Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an countries, patents did not contain claims before the 1970s. It was then often difficult (and subjective) 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 system exist:
  • the central claiming system, according to which the claims identify the "centre" of the patented invention
    An invention is a novel composition, device, or process. An invention may be derived from a pre-existing model or idea, or it could be independently conceived, in which case it may be a radical breakthrough. In addition, there is cultural invention, which is an innovative set of useful social...

    . The exact scope of the protection depends on the actual nature of the inventor’s contribution to the art in the concerned technology
    Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...

  • the peripheral claiming system, according to which the claims identify the exact periphery, or boundary, of the conferred protection. In this system, the burden of drafting good claims is much higher on the patent applicant (or on his counsel
    Patent attorney
    A patent attorney is an attorney who has the specialized qualifications necessary for representing clients in obtaining patents and acting in all matters and procedures relating to patent law and practice, such as filing an opposition...

    ). The applicant receives the protection he or she requested and almost nothing more, provided that the invention is new
    Novelty (patent)
    Novelty is a patentability requirement. An invention is not patentable if the claimed subject matter was disclosed before the date of filing, or before the date of priority if a priority is claimed, of the patent application....

     and non-obvious
    Inventive step and non-obviousness
    The inventive step and non-obviousness reflect a same general patentability requirement present in most patent laws, according to which an invention should be sufficiently inventive — i.e., non-obvious — in order to be patented....

    . This theoretically makes it easier for third parties to examine whether infringement
    Patent infringement
    Patent infringement is the commission of a prohibited act with respect to a patented invention without permission from the patent holder. Permission may typically be granted in the form of a license. The definition of patent infringement may vary by jurisdiction, but it typically includes using or...

     may exist or not.

No patent system today is a purely either central or peripheral, but the system used in Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 and most of the other countries of continental Europe
Continental Europe
Continental Europe, also referred to as mainland Europe or simply the Continent, is the continent of Europe, explicitly excluding European islands....

 is considered more central than the system currently used in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and especially Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, which are more peripheral. In recent years, Japan's system has become more peripheral, while the system used in the United States has become less peripheral.

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.

Under the European Patent Convention
European Patent Convention
The Convention on the Grant of European Patents of 5 October 1973, commonly known as the European Patent Convention , is a multilateral treaty instituting the European Patent Organisation and providing an autonomous legal system according to which European patents are granted...

 (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
Nail (engineering)
In woodworking and construction, a nail is a pin-shaped, sharp object of hard metal or alloy used as a fastener. Formerly wrought iron, today's nails are typically made of steel, often dipped or coated to prevent corrosion in harsh conditions or improve adhesion...

, a rivet
A rivet is a permanent mechanical fastener. Before being installed a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole, and the tail is upset, or bucked A rivet...

) or functional (e.g. fastening
A fastener is a hardware device that mechanically joins or affixes two or more objects together.Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid to a container,...


A claim may include the following parts (the terminology and requirements may however significantly differ from one legislation to another):
  • A preamble that recites the class of the invention, and optionally its primary properties, purpose, or field: "An apparatus..." "A therapeutic method for treating cancer..." "A composition having an affinity for protein X..." This preamble may also reference another claim and refine it, e.g., "The method of claim 1..." (See "dependent claim" below.). However, under the European Patent Convention, the preamble has a different meaning. In an independent claim, it is everything which precedes the expression "characterized in that" or "characterized by".

  • A "transitional" phrase
    Transitional phrase
    A transitional phrase, in United States patent law, is a phrase that links the preamble of a patent claim to the specific elements set forth in the claim which define what the invention itself actually is...

     that characterizes the elements that follow. The phrases "comprising", "containing" and "including" are most often used and (under some patent laws, specifically US) preferable, as it means "having at least the following elements..." and are therefore open (inclusive) and do not exclude additional limitations. The phrases "consisting of" and "consisting essentially of" are (under some patent laws, specifically US) more limiting, as they mean "having all and only" or "virtually only" and are therefore closed (exclusive). In the US, the phrase "consisting of" excludes additional limitations, while the phrase "consisting essentially of" excludes additional limitations that would "materially affect the basic and novel characteristic(s) of the claimed invention".

  • A set of "limitations" that together describe the invention: "an X, a Y, and a Z connected to the X and the Y." The elements should be described as though they interact or cooperate to achieve the desired result. The distinction between elements and limitations is explained in the article All elements test
    All elements test
    The all elements rule or all limitations rule is a legal test used in US patent law to determine whether a given reference anticipates a patent claim. The rule is also applicable to an obviousness analysis...


  • Optionally, a purpose clause that further describes the overall operation of the invention, or the goal that the invention achieves ("wherein the Z simultaneously controls the X and Y," or "wherein the Z accomplishes purpose W by controlling X and Y," etc.)

Interpretation or claim construction

The claims often comprise 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 may 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
Sufficiency of disclosure
Most patent law systems require that a patent application disclose a claimed invention in sufficient detail for the notional person skilled in the art to carry out that claimed invention. This requirement is often known as sufficiency of disclosure or enablement, depending on the...

). In U.S. law, a claim is interpreted in a Markman hearing
Markman hearing
A Markman hearing is a pretrial hearing in a U.S. District Court during which a judge examines evidence from all parties on the appropriate meanings of relevant key words used in a patent claim, when patent infringement is alleged by a plaintiff...

. The Public Patent Foundation
Public Patent Foundation
Public Patent Foundation, or PUBPAT, is a nonprofit organization that seeks to limit perceived abuse of the United States patent system. It was founded in 2003 by Dan Ravicher. , there was growing concern by many technology professionals over the number of patents granted that are either too...

 has constructed Free Claim Construction Dictionaries.
Construction, whether of a patent or any other document, is of course not directly concerned with what the author meant to say. There is no window into the mind of the patentee or the author of any other document. Construction is objective in the sense that it is concerned with what a reasonable person to whom the utterance was addressed would have understood the author to be using the words to mean. Notice, however, that it is not, as is sometimes said, "the meaning of the words the author used", but rather what the notional addressee would have understood the author to mean by using those words. The meaning of words is a matter of convention, governed by rules, which can be found in dictionaries and grammars. What the author would have been understood to mean by using those words is not simply a matter of rules. It is highly sensitive to the context of and background to the particular utterance. It depends not only upon the words the author has chosen but also upon the identity of the audience he is taken to have been addressing and the knowledge and assumptions which one attributes to that audience.

Basic types and categories

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 embodiments usually correspond to a dependent claim or could form the basis of a dependent claim. Each dependent claim is, by law, more narrow than the independent claim upon which it depends. Accordingly, it might appear that there would be little purpose to the dependent claim. In reality, however, there are at least three advantages to the patent applicant in submitting and obtaining a full string of dependent claims:
  • Clarification of the independent claim language: Independent claims are typically written with very broad terms, to avoid permitting competitors to circumvent the claim by altering some aspect of the basic design. But when a broad term is used, it may raise a question as to the scope of the term itself. For example, does a "base" include 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 it does. 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 base 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 filling, 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.

  • Claim differentiation: In United States patent law, under the doctrine of claim differentiation, each claim is presumed to cover a different aspect of the invention than in each other claim. This doctrine may be relied upon to help maintain broad claim scope in the case where a claim standing alone might be construed as having either a broad or a narrow interpretation. If a dependent claim is added that depends from this "parent" claim but is specifically drawn to the narrower interpretation, then the parent claim must necessarily be different - i.e., it must be the broader interpretation. As construed in the courts, the doctrine of claim differentiation 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 4 legs, the independent claim is not limited to what is recited in the dependent claim. The dependent claim protects chairs with 4 legs, and the independent claim protects chairs with 4 legs as well as chairs having 2, 3, 5 or more legs.

    Under the European Patent Convention
    European Patent Convention
    The Convention on the Grant of European Patents of 5 October 1973, commonly known as the European Patent Convention , is a multilateral treaty instituting the European Patent Organisation and providing an autonomous legal system according to which European patents are granted...

    , 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 Canada and 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".

    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.

    See also

    • Catnic Components Ltd. v. Hill & Smith Ltd.
      Catnic Components Ltd. v. Hill & Smith Ltd.
      Catnic Components Ltd. v. Hill & Smith Ltd. R.P.C. 183 is a leading House of Lords decision on the nature of a patent and in particular the methods of claim construction.-Background:...

    • Claims under the European Patent Convention
      Claims under the European Patent Convention
      Article 84 of the European Patent Convention defines the function of the claims under the European Patent Convention, the function being to define the matter, i.e. the invention, for which patent protection is sought. This legal provision also imposes that the claims must be clear, concise as well...

    • Clearance search and opinion
    • Disclaimer
      Disclaimer (patent)
      In patent law, a disclaimer are words identifying, in a claim, subject-matter that is not claimed. By extension, a disclaimer may also mean the action of introduction a negative limitation in a claim, i.e. "an amendment to a claim resulting in the incorporation therein of a "negative" technical...

    • Doctrine of equivalents
      Doctrine of equivalents
      The doctrine of equivalents is a legal rule in most of the world's patent systems that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed...

    • Probatio diabolica
      Probatio diabolica
      Probatio diabolica is a legal requirement to achieve an impossible proof. Where a legal system would appear to require an impossible proof, the remedies are reversing the burden of proof, or giving additional rights to the individual facing the probatio diabolica.In essence the lack of proof that...

      , in relation to product-by-process claims

    Further reading

    • The construction of product-by-process claims, 11th European Patent Judges' Symposium
      European Patent Judges' Symposium
      The European Patent Judges' Symposium is a biennial symposium, with the claimed aim of providing a platform for national judges from legal systems with differing traditions to exchange experiences and to thereby promote mutual understanding in the development of European patent law...

      , Copenhagen, Official Journal of the EPO 2003, Special Edition, No. 2, p. 20-75 (pdf)

    External links