Proper antecedent basis
Elements within a patent claim must establish a proper antecedent basis. This requires that an element be introduced for the first time using the indefinite article “a” or “an.” When that same element is mentioned again, the definite article “the” is used. Beyond grammatical correctness, maintaining a proper antecedent basis is also a legal requirement.
The following claim set illustrates this concept:
- A device, comprising:
- a pencil; and
- a light attached to the pencil.
- The device recited in claim 1 wherein the light is detachably attached to the pencil.
- The device recited in claim 2 wherein the pencil is red in color.
Professional Tip:
Although the articles “the” and “said” are functionally interchangeable in claim drafting (e.g., “the pencil” or “said pencil”), the latter has become increasingly archaic. In many jurisdictions, the prevailing trend favors the use of plain language, even in legal documentation. If your patent becomes subject to litigation in the United States, the claims may be interpreted by a jury that does not have legal training, and excessive reliance on “legalese” is unlikely to engage them favorably.
In Claim 1, the “pencil” is introduced for the first time using the expression “a pencil.” Likewise, the light element is initially introduced as “a light.” However, when the claim later specifies that the light is attached to the pencil, the reference becomes “the pencil.” The definite article “the” indicates that the pencil being referenced is the same one previously defined in the claim; otherwise ambiguity - would arise whether it refers to the same pencil or to a different one.
If a subsequent claim must refer to a different pencil, the first pencil must be distinguished from the second. One approach is to recite a “first” element and then a “second” element, and so forth. Another option, suitable when only a small number of elements are involved, is to refer to the first as “an” element and the second as “another” element. Examples include:
- A first widget, connected to a second widget, wherein the first widget…
- A foomerantz, coupled to another foomerantz, wherein another foomerantz has a higher capacitance than the foomerantz…
Within each new claim set, the antecedent basis must be established again. Consequently, when drafting a subsequent claim set, the patent drafter must once more introduce a proper antecedent basis for the element “pencil.” In practical terms, this means that every new claim must be drafted independently from the others.
If we prepare a new claim (Claim 4) for our pencil invention, it might read:
- A device, comprising:
- a pencil; and
- a light attached to the pencil, wherein the light is detachably attached to the pencil.
Reference Numerals and Parenthetical Expressions
In certain jurisdictions, claims are encouraged and/or required to include reference numerals corresponding to the labels assigned to particular elements in the drawings of the patent application. In PCT international applications, these reference numerals should preferably appear in parentheses immediately after the relevant elements within the claims. For example, if Figure 1 of a patent application shows a computer memory labeled “123,” any reference to that specific computer memory element in the claims would be followed by “(123).”
In jurisdictions where reference numerals are encouraged, this practice improves the readability of the claims by creating a direct connection between the claims and the drawings. However, when numerous different embodiments are disclosed, typically only the most significant embodiments need to be reflected in the claim(s) and identified in this manner. In many jurisdictions, patent legislation explicitly provides that reference numerals do not limit the scope of the subject matter defined by the claims. Their only function is to improve the clarity and readability of the claims. A patent drafter may even include a statement within the description explicitly clarifying this point.
By contrast, in certain countries most notably the United States patent drafters typically avoid, or may even be prohibited from using, such reference numerals. This approach likely stems from the concern that alleged infringers and courts could interpret these numerals as limiting the claims. Adding descriptive text alongside reference numerals in parentheses may also introduce ambiguity. For instance, expressions such as “securing means (screw 13, nail 14)” or “valve assembly (valve seat 23, valve element 27 & valve seat 28)” might be interpreted not merely as reference indicators but as "special features." As a result, uncertainty may arise as to whether the features accompanying the reference signs impose additional limitations.
In certain jurisdictions, clarity issues may also arise from parenthetical expressions that do not contain reference numerals, for example “(concrete) molded brick,” which may therefore be rejected. Conversely, expressions with a commonly accepted meaning are allowed, such as “(meth)acrylate,” which is widely recognized as an abbreviation for “acrylate and methacrylate.” Parentheses used within chemical or mathematical formulas are generally acceptable and do not raise objections.
It is important to note that inserting reference numerals into the claims does not mean that the associated drawings are incorporated into the claims themselves something that is considered impermissible in most jurisdictions. Accordingly, claims should always be drafted with the same level of precision and clarity as if no drawings existed.
Example
A claim containing reference numerals may read:
- An apparatus, comprising:
- a plurality of printed pages (11);
- a binding (14) configured to hold the printed pages (11) together; and
- a cover (21) attached to the binding (14).
The numbers in parentheses represent the reference numerals used as labels in the drawings accompanying the patent application.
Claim phrases
We have already observed that certain terms, such as “comprising,” carry a specific meaning in the context of patent claims. Likewise, other terms acquire particular interpretations when used in claims. Some words serve to further characterize a structure or to define a function associated with a particular structure. Examples include “wherein,” “whereby,” “such that,” and “so as to.” A patent drafter must understand how courts in the relevant jurisdictions interpret these expressions and employ them appropriately in accordance with the intended scope of protection.
For instance, a “wherein clause” is commonly used to describe a function, operation, or outcome that necessarily follows from the previously recited structure or function of the claim. Therefore, “wherein clauses” should be used when the stated result logically and inevitably derives from the recited structure or function.
Example
We want to claim a folder for storing files. Using “wherein,” the claim might read:
- A folder for keeping files, wherein the folder is configured to receive the files…
In claim drafting, the term “wherein” is also used in dependent claims to introduce additional selections or features of elements, as will be explained later in section 3.5 on claim dependency.
Multiple elements
Many patent offices require that claims recite at least two elements. A patent claim containing very few limitations can become excessively broad.
The rationale for this requirement becomes clear when comparing two claims.
Example
Compare:
A computer, comprising:
- a processor.
with:
A computer, comprising:
- a processor;
- a memory; and
- a bus configured to transmit data between the memory and the processor.
The first claim conveys very little about the computer other than that it includes a processor. While the specification will define what is meant by a processor, and processors are known to exist in the prior art, the applicant appears to be claiming virtually anything that contains a processor particularly if the preamble is not interpreted as limiting.
Such a claim is excessively broad: it would read on (see Module II, section 1.2) a box used to ship a processor, since the claim provides no further information about computers beyond indicating that they are structures containing processors.
The second claim introduces substantially more structural detail and definition regarding the computer. Consequently, its scope is narrower than that of the first claim.
2.3 Two part claims or improvement claims
Most of the principles explained in the previous sections regarding the structure and details of a claim also apply to claims drafted in the two-part format. This format is also referred to as an improvement claim or (in the United States) a Jepson claim.21 In a two-part claim, the preamble identifies the most relevant known prior art, while the body of the claim defines the improvement represented by the invention. The preamble and the body are linked by a specific transitional phrase indicating that the claim is written in two parts. Thus, two-part claims still consist of a preamble, a transitional phrase, and a body; however, the preamble serves as a statement (an implied admission) of the closest prior art, the transitional phrase is typically “characterized by” or “characterized in that” in Europe, or “wherein the improvement comprises” in the United States, and the body sets out the element(s) that the applicant considers novel (i.e., not disclosed in the closest prior art).
Example 1
- A pencil having an eraser attached to one end of the pencil, wherein the improvement comprises a light attached to the pencil.
In this claim, “a pencil having an eraser” represents the relevant known prior art, while the claimed improvement is the addition of the attached light.
Using the standard claim format, the claim could be rewritten without changing its scope as follows:
- A writing device, comprising:
- a pencil having an elongated structure including two ends;
- an eraser attached to one end of the pencil; and
- a light attached to the pencil.
Example 2
- A writing device, 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 pencil, characterized in that the light is attached to the center of the pencil.
In this claim, the applicant acknowledges that a writing device including a pencil with an eraser on one end and a light is part of the known prior art, and identifies the improvement as the specific placement of the light at the center of the pencil.
As demonstrated in Example 2, the two-part claim format clearly distinguishes the inventive feature of the claimed invention from the prior art. However, patent drafters should recognize that by adopting the two-part claim format, the applicant implicitly concedes that the subject matter described in the first portion of the claim was not novel at the filing (or priority) date of the patent application.
Certain jurisdictions, such as the European Patent Office (EPO), encourage the use of the two-part format when it is considered appropriate. The EPO recommends that applicants employ the two-part formulation in claims, for example, when it is clear that the invention represents a specific improvement over an existing combination of elements or steps. As is often the case with rules introduced for administrative convenience, this “preference” is applied with some degree of flexibility in practice (a brief review of patents granted by the EPO reveals numerous claims that do not follow the two-part structure).
Accordingly, patent drafters should carefully evaluate whether a two-part claim format aligns with their client’s best interests, given that it requires an explicit acknowledgment of the prior art in the first part of the claim. Some patent drafters prefer to prepare their claims initially in the standard format and then determine whether the examiner requires conversion to the two part format. In other situations, particularly when the client intends to file exclusively with the EPO, drafting the claims from the outset in the two-part format may be the most suitable approach, depending on the nature of the invention and the available prior art.
The EPO recommends that the first portion of such claims include a statement identifying “the subject matter of the invention”-namely, the general technical category of the apparatus, process, or other subject matter to which the invention relates-followed by a statement describing "those technical features which are necessary for the definition of the claimed subject matter but which, in combination, form part of the prior art."²² This statement of prior art features applies only to independent claims and not to dependent claims.
Consequently, such statements are required only when prior art features are relevant to the invention. For example, if the invention relates to a photographic camera but the inventive step concerns solely an improvement to the shutter, it would typically be sufficient for the first portion of the claim to read: “A photographic camera including a focal plane shutter…” There would be no need to mention other known camera components, such as the lens or the view-finder, unless such elements are essential components of a camera.
The second part, or characterizing portion, should then summarize the features that the invention adds beyond the prior art-that is, the technical features for which protection is sought in combination with the features set out in the first part.
Although the EPO expresses a preference for the use of two-part claims, it recognizes that this format is not appropriate in every situation. In certain cases, the nature of the invention may render the two-part structure unsuitable, for example where it would produce a distorted or misleading description of either the invention or the prior art. Examples of inventions that may require a different form of claim presentation include:
- The combination of known integers of equal status, where the inventive step resides solely in the combination itself.
- The modification of a known chemical process, rather than an addition to it-for example, by omitting a substance or replacing one substance with another.
- A complex system comprising functionally interrelated components, where the inventive step relates to modifications in several of those components or in the relationships between them.
In the first two examples, the two-part claim format may appear artificial and inappropriate, whereas in the third example it could lead to a claim that is excessively long and unnecessarily complicated.
Another situation in which the two-part claim format may be unsuitable arises when the invention relates to a new chemical compound or a group of new chemical compounds.
The EPO further notes that additional situations may occur in which the applicant can present convincing reasons for structuring the claim in a form other than the two-part format.
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