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July 2020 Edition

Specification Drafting – Best Practices

Drafting a patent specification

There are many features of a good patent specification that go beyond the basic legal requirements. A good specification should contain everything that will be needed during the prosecution of an application and during the life of any patent issuing from that application. While claims can be altered during prosecution, the specification cannot.

Some general guidelines to consider when drafting a patent specification include making sure that the specification: (1) fully supports the claims; (2) broadly describes the disclosed methods and apparatuses; (3) avoids specification drafting pitfalls; (4) is written with future prosecution in mind; and (5) is written with future enforcement in mind. These are each discussed in greater detail below.

Fully support the claims

The claims of a patent will be interpreted in light of the specification. As a result, an applicant should provide guidance in the specification for interpreting the claims. Without this guidance, the claims may be interpreted in ways that an applicant disagrees with.

The specification should provide examples of every important element or operation described in the claims using the same language as the claim does. This will both ensure that the element or operation is fully enabled and provide valuable guidance to a patent examiner or a court when they must interpret the meaning of the element or operation.

The specification should adequately define every term used in the claims, identifying what they mean or how they operate. This is particularly true for any non-standard term contained in the claims. During prosecution or enforcement, an examiner or court will have to interpret the meaning of the terms used in the claim. Providing a definition in the specification avoids uncertainty in such interpretation.

Every abbreviation used in the claims or specification should be defined the first time it is used. An abbreviation may be in common use in the relevant art. However, if the abbreviation used in the claims is not defined in the specification, the Examiner could assert that the claim term is unclear.

In any computer-implemented applications, the specification should clearly identify structure for a controller that implements the operation in the claims, as well as for any memory that contains information or instructions used by the controller. This can help avoid rejections under 35 U.S.C. § 101.

Any actual or potential means-plus-function elements used in the claims should be described in the specification using specific structural description. Terms that are considered means-plus-function terms will be construed under 35 U.S.C. § 112(f) to cover the corresponding structure described in the specification and equivalents thereof. Any claim element without adequate structure could be rejected for lack of enablement. This is particularly important given recent trends in the U.S. Patent Office to interpret some claim elements as being mean-plus-function elements even when they fail to use “means for” language.

Broadly describe the disclosed methods and apparatuses

Since the claims will be interpreted in light of the specification, it is important to describe the elements and operations of the claims in as much detail as possible. This detail can help avoid overly narrow interpretation of claim elements.  

Where possible, multiple examples of physical elements should be described. For example, if a fastening device is described, the applicant might state in the specification that the fastening device could be formed by a screw, a bolt, a clamp, or any other element. This additional detail will help broaden the interpretation of the element and can provide support for amendments to narrow the claim should that be necessary during prosecution.

It can also be helpful to describe any disclosed apparatus or method in greater detail than used in the claims, and to describe alternate embodiments of the disclosed apparatuses and methods. Such additional detail or alternate embodiments can provide support for future amendments to the claims that may be necessary to overcome prior art rejections during prosecution. Without additional details, it may be impossible to find support for significant claim amendments during prosecution. The disclosure of additional details and alternate embodiments can also provide the support necessary to file continuation applications that receive the benefit of the filing date of the parent application.

Avoid specification drafting pitfalls

In addition to making certain that the details in the specification are sufficient, it is important to avoid some pitfalls in the content of the specification that be harmful to the applicant during prosecution and enforcement.

Any use of the term “invention” can unintentionally limit the scope of the claims. Some courts have interpreted statements in a specification regarding the “invention” as limiting what the inventor intended their invention to be and therefore what the claims might cover. This could potentially limit the scope of the claims even when the plain language of the claims might be broader in nature. Avoiding the term “invention” in the specification will eliminate this possibility.

Anything written in the Background section of the specification may be interpreted by the examiner as admitted prior art during prosecution, even if it is not actually prior art. This can require the applicant to waste resources arguing against such an interpretation, can unnecessarily put arguments into the record, and can potentially result in claims not being allowed. It is generally advisable to describe the Background section of the application as succinctly as possible. It is likewise advisable to avoid the use of drawings in the Background unless such drawings are necessary.

The disclosure in the specification of a single embodiment for an apparatus, method, element, or operation without acknowledgement of alternatives can cause some courts to interpret all or part of the claim as covering only what was specifically disclosed. This danger can be mitigated by stating in the specification that what is disclosed are exemplary embodiments and not a preclusive definition of the invention.

Write with future prosecution in mind

Although the application is written before prosecution begins, the applicant should nevertheless draft the application with thought as to how it can be used or how it will be interpreted during prosecution.

Even before the examiner completes a prior art search and issues a first office action, the applicant will know much about the state of the technology. The applicant may be aware of prior art documents that must be submitted in an IDS. An applicant will certainly draft the claims to distinguish known prior art. But the specification should also be drafted to highlight patentable differences between the disclosed apparatuses or methods and known prior art.

In some cases, the applicant may be aware that the claimed apparatuses or methods are very similar to existing prior art. The applicant may suspect that it will be necessary to argue so-called secondary considerations (e.g., commercial success, long felt need, failure of others, etc.) to avoid an obviousness rejection. In such a situation it can be helpful to put information about those secondary considerations in the specification. Similarly, if the applicant is aware of any specific prior art that it suspects will be cited against the application, it can be helpful to augment disclosure in the specification to highlight features that will distinguish the disclosed apparatuses or methods from what is in the prior art. By providing such information to the examiner in the specification, the applicant can potentially convince the examiner to avoid making certain rejections before the issuance of a first office action.

Write with future enforcement in mind

Although the application is also written before the issuance of a patent, the applicant should nevertheless draft the application with thought as to how it can be used or how it will be interpreted after a patent issues and the patent must be enforced.

One possible use of a patent is to prevent a competitor from copying the applicant’s product. To this end, it is important to disclose the most likely commercial embodiment of the invention as well as any other particularly valuable commercial embodiments. A court interpreting the claims will look to the specification for guidance. If the specification discloses an embodiment that is similar to what the applicant is actually producing, it is more likely that the court will interpret the claims as reading on that product.

Another possible use of a patent is to prevent a competitor from using a product that is similar, but not identical, to the applicant’s product. It is therefore also important to disclose embodiments of the claimed invention that the applicant thinks might be included in competing products. Again, the court will look to interpret the claims in light of the specification. If the specification discloses an embodiment that is similar to what a competitor is producing, it is more likely that the court will interpret the claims as reading on that product.


No application is perfect, and often decisions must be made as to how much time and effort can be expended preparing a given application. It may not be possible to include as much detail as is suggested above. Nevertheless, it is important for an applicant to consider all these details when drafting an application so that the applicant can make an informed decision as to where to devote its efforts and resources.

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