Fundamentals of Claim Drafting
When an inventor approaches a patent drafter with the intention of submitting a patent application, the patent drafter must first address several fundamental questions:n/
- What exactly has been invented?
- What constitutes the core inventive concept underlying the invention?
- Does the inventor clearly understand the subject matter they intend to protect?
- In what manner should the invention be claimed?
1. Theory of the Patent Claim
1.1 Overview: Inventions, Embodiments, and Claims
Claims establish the boundaries (the scope) of the protection conferred by a patent, in much the same way that a physical barrier such as a fence marks the limits of a parcel of real property. Accordingly, the claims function as a written expression of the abstract idea conceived by the inventor. While courts across different jurisdictions may apply varying legal principles when construing claims, the most broadly accepted approach is that the claims define the outer perimeter of patent protection (known as peripheral claiming). The claims communicate to the public, in a clear and concise manner, what the applicant regards as their invention. As a judge of the United States Court of Appeals for the Federal Circuit (and its predecessor, the Court of Customs and Patent Appeals) famously stated in 1990, “The name of the game is the claim.”
The patent drafter must appreciate the differences among three legal concepts associated with patents: inventions, embodiments, and claims.
- An invention is an idea or concept existing solely within the inventor’s mind and does not possess a physical form.
- An embodiment of an invention is a physical implementation or realization of that invention in the tangible world.
- The claims must cover at least one embodiment of the invention
however, the strongest patent claims are those that protect the invention itself, such that no physical implementation of the invention can be made, used, or sold without infringing the claims.
A logical implication of the distinctions among the invention, embodiments, and claims is that the claims themselves do not define the invention. Even so, patent professionals frequently use the expression claimed invention to describe the subject matter set forth in the claims of a patent application or an issued patent.
Example
An inventor develops the first cup incorporating a handle. They produce a physical embodiment of the invention in the form of a red clay cup with a handle. The patent drafter could elect to claim only that particular embodiment the red clay cup with a handle but doing so would permit others to manufacture non-infringing alternatives, such as plastic cups with handles.
If the patent drafter properly comprehends the invention, they will draft the invention of a cup with a handle as the broadest claim, while preserving the particular embodiment (the red clay cup) for a narrower, dependent claim (see section 1.2 of this module for further explanation of broader and narrower claims).
During the early development of patent law, patent applications did not contain claims. Instead, the scope of the invention was determined during patent infringement litigation through analysis of the inventor’s written description. This method soon became unworkable, resulting in the evolution of the modern patent claim system, under which claims distinctly define the boundaries of patent protection. Originally, claims were intended to provide notice to the public by describing what the inventor considered to be their invention at the time of filing. Today, claims occupy a central role within the patent system and determine the extent of the protection granted. They are generally the first portion of a patent to be reviewed and scrutinized by readers, including courts. In a substantive examination patent system (see Module II, section 1.1), the patent examiner also evaluates the claims before the patent is granted, thereby giving both the courts and the public a degree of confidence that the patent does not exceed the proper scope of the invention.
As repeatedly emphasized throughout this manual, the description contained in the patent application must fully support the claims. Accordingly, once the claims have been drafted and the description has been prepared, the patent drafter must review both sections to verify that each claim is properly supported. The terminology the words and expressions used in the claims should also consistently appear within the description. A claim that is not supported by the description can be readily invalidated for lack of basis. For example, if a patent drafter claims a glass table with four legs, the description must provide support for such a table not merely a general description of wooden tables or tables having three legs. In jurisdictions where the support requirement is rigorously applied, such as at the European Patent Office (EPO), the description must also expressly disclose at least one embodiment that clearly illustrates the combination of glass and four legs.
Although jurisdictions may vary in terms of formatting requirements and interpretative practices, the fundamental principles defining a well‑drafted patent claim remain largely consistent across the world. The EPO summarizes these principles as follows:
The application must contain “one or more claims.” These must:
- “define the matter for which protection is sought”;
- “be clear and concise”; and
- “be supported by the description.”
Since the extent of the protection conferred by a patent or application is determined by the claims (interpreted with the assistance of the description and the drawings), the clarity of the claims is of paramount importance.
In general, the concept of an invention is closely associated with the concept of technology, which is broadly understood as the application of scientific knowledge to address practical problems. The EPO therefore recommends that claims be drafted in terms of the “technical features of the invention” meaning that claims should avoid statements relating to commercial advantages or other non‑technical aspects, although “statements of purpose are allowed if they assist in defining the invention.”
This recommendation represents sound guidance for patent drafters in any jurisdiction.
Broad and Narrow Claims
If the responsibility of the patent examiner is to ensure that a typical patent claim does not exceed the scope of its invention in other words, the claim’s theoretical maximum then who bears the responsibility of ensuring that the claims approach that maximum?
The straightforward answer is that the patent drafter is responsible for aiming to draft a set of claims that is sufficiently broad to cover different aspects of the invention at varying levels of specificity. However, the patent drafter may not always wish the claims to reach the theoretical maximum, since future litigation may introduce invalidity arguments that neither the applicant nor the examiner anticipated. Consequently, narrower claims can function as a fallback position if the broadest claims are later invalidated.
A narrower group of claims may still survive litigation and may be adequate to provide effective protection against a patent infringer.
While this approach appears simple in theory, it becomes significantly more complicated in practice. At the stage of drafting a patent application, it is challenging to determine the legitimate scope of protection for an invention, since that scope can only be assessed in light of all relevant prior art. A prior art search can never be entirely comprehensive, and an applicant may discover only after filing that part of the originally claimed subject matter lacks novelty. The situation is further complicated by the fact that, in many jurisdictions, patent applications that were filed earlier but had not yet been published at the time of the applicant’s filing may later emerge as novelty‑destroying prior art.
As a general principle, the description of a patent application should therefore disclose the claimed subject matter through embodiments that implement the inventive concept of the invention, while the claims should clearly define the subject matter for which protection is sought.
Although some jurisdictions restrict the extent to which an applicant may amend or replace claims on their own initiative, amendments are frequently permitted during patent prosecution or examination when the patent examiner raises an objection. The patent drafter may therefore have some flexibility to modify pending claims in order to avoid overlap with newly identified prior art, to satisfy legal requirements that have not yet been met, or to reflect evolving strategic interests regarding the desired scope of protection. In certain jurisdictions, there may also be opportunities to respond to hindsight for example, when the client or the patent drafter later realizes that the claims as originally filed could have been drafted more broadly.
Patent Protection and Infringement: All-Elements Rule
As discussed in earlier modules, a patent generally provides the patent owner with the exclusive right subject to certain exceptions to determine who may make, use, sell, offer for sale, or import any product or process defined by the patent claims. Put differently, competitors are required to obtain authorization from the patentee in order to make, use, or otherwise exploit the claimed invention. In the absence of such authorization, they infringe the patent claims and, consequently, the patent itself.
Accordingly, when drafting claims, patent drafters should consistently seek to ensure that competitors whether existing or potential are unable to avoid the claimed invention while still taking advantage of the underlying “ideas” or “inventive concepts” without infringing the claims.
Example
A patent claim reads:
- A writing apparatus, comprising:
- a pencil having an elongated structure including two ends and a center between the ends;
- an eraser attached to one end of the pencil; and
- a light attached to the center of the pencil.
Under the all-elements rule, a competitor infringes the claim if it manufactures a writing device including all of the following:
1- a pencil with an elongated structure, including two ends and a center between the ends;
2- an eraser attached to one end of the pencil; and
3- a light attached to the center of the pencil.
One competitor manufactures a writing device including a pencil and an eraser attached to one end of the pencil, but without any light attached to the pencil. Another competitor manufactures a pencil having an eraser attached to one end and a light likewise attached to one end of the pencil (that is, not attached to the center of the pencil).
In these situations, patent infringement does not occur.
But What Exactly Is Meant by Infringing a Patent Claim?
Every alleged infringement committed by a third party is linked to what is referred to as an accused embodiment, which may consist either of a physical object (for example, an apparatus manufactured by a third party or a chemical compound sold by a third party) or an activity (for example, a manufacturing process carried out by a third party). In certain situations, the third party may even own a separate patent relating to the accused embodiment.
To assess whether the accused embodiment infringes the patent claims, the accused embodiment must be directly compared with the subject matter defined in the claims.
The fundamental principle governing patent claim infringement is commonly known as the all-elements rule. In essence, this principle requires that every element of a claim be present in the accused embodiment of the third party in order to establish patent infringement.
As demonstrated by the above example, the comparison between the accused embodiment and the allegedly infringed claim should be performed on an element-by-element basis an approach broadly recognized across many jurisdictions. The term element is widely used internationally and is often employed interchangeably with the term technical feature, as used in the European Patent Convention (EPC), or limitation, as used in U.S. patent law and practice.
Depending on the nature of the claimed subject matter, different categories of elements may be included, such as the following:
- Structural elements are characterized by what they are, for example: “a screw,” “a DVD,” “hydrogen peroxide,” “talc,” etc.
- Functional elements are characterized by the functions they perform, for example: “a fastening means,” “a computer-readable storage medium,” “an oxidizing agent,” “a pharmaceutically acceptable excipient,” etc.
- Relational elements define relationships between other elements, for example: “attached,” “electrically connected,” “dissolved in the same solution,” etc.
- Intentional elements define an intended purpose or objective and are commonly introduced by the preposition for, for example: “for coagulation,” “for treating cancer,” etc.
- Parametric elements consist of parameters (that is, values corresponding to directly measurable properties), for example: the flexural strength of a metal, the resistance of an electric conductor, the melting point of a substance, etc.
- Activity elements describe the steps involved in defining the subject matter of a process or activity claim and are generally introduced using verbs in gerund form, for example:
“fixing” together, “reading” information from, “reacting” with, etc.
Patent Claim Format
There is no single globally standardized format for patent claims, and drafting practices frequently vary among jurisdictions. Nevertheless, certain commonly accepted formats and conventions are broadly recognized and applied, as discussed in this section.
Unless stated otherwise, the rules addressed in this manual are based on the Patent Cooperation Treaty (PCT).
Traditionally, a patent claim is drafted as a single sentence written in the present tense. Every claim starts with a capital letter and concludes with a period. Periods should not appear elsewhere within the claim except when used in abbreviations. Semicolons are typically employed to separate clauses and phrases inside the claim. Although a patent claim is formally considered a single sentence, it is often extensively punctuated because of the complexity of the subject matter being expressed.
All claims are numbered consecutively, and each number functions as the identifier for the corresponding claim (for example, “Claim 1”).
The claims are properly grouped and numbered and are presented in a separate section entitled “Claims”. This section must be clearly distinguished from the remainder of the application, usually through the use of page breaks. In most patent applications and granted patents, the claims section is positioned near the end of the document.
However, in the published documents of certain patent offices including the China National Intellectual Property Administration (CNIPA), the Japan Patent Office (JPO), and the Korean Intellectual Property Office (KIPO) the claims section is placed before the description section.
In the United States, the claims section and the description section are generally differentiated by introductory phrases such as “I/we claim” or “What is claimed is.”
The Secretariat of WIPO assumes no liability or responsibility with regard to the transformation or translation of the original content.
World Intellectual Property Organization (WIPO) (2023). WIPO Patent Drafting Manual, Second edition. Geneva: WIPO. DOI: 10.34667/tind.44657