How to read a patent specification

Tuesday 8th November 2016

Reading and understanding patent specifications is key to determining whether or not your product infringes another's patent rights.  As with any technical or legal document, there is a method to reading patent specifications and understanding the distinct patent drafting practices that have evolved over the years. This article gives a basic overview of the contents of a patent and will assist you to read and make sense of patent specifications relevant to your field of technology.


This article is published in Chemistry in New Zealand (CiNZ), the journal of the New Zealand Institute of Chemistry (NZIC).  The NZIC represents members involved in the chemistry profession including those who study, practice, teach, promote and manage chemistry.


It’s probably fair to say that most scientists never read patent specifications.  If they do have occasion to come across one, they are generally appalled at the wordiness, bold statements claiming everything under the sun, and general incomprehensibility of the text.  However, as with any technical or legal document, there is a method to the madness.  There are distinct practices that have evolved over the years to meet legislative requirements and ensure that the patent is less vulnerable to challenges. 

Patent specifications (and the claims in particular) are key to determining whether you infringe patent rights in a particular country, i.e. whether you have “freedom to operate”.  They are also an invaluable resource to gain knowledge to guide your own R&D, or gather intelligence on other people’s activities. 

What is a patent specification?

A patent specification is a written description of an invention that includes details of how to make and use the invention.  Patent specifications are published by the national patent office and can generally be accessed through the patent search portal on their website.  For example specifications for granted New Zealand patents can be accessed through the Intellectual Property Office of New Zealand (IPONZ) website.  Australian patent specifications can be accessed from IP Australia’s AusPat.

The key principle of the patent system is that the inventor discloses their invention to the public, and in return the state grants the inventor a limited term monopoly right over the invention.  To satisfy the disclosure requirement, the specification includes a description of the invention (see below).  The actual monopoly right granted to the inventor is set out in strictly defined terms in the claims of the specification (see below).  In this way, the patent specification is essentially a quid pro quo contract between the inventor and state. 

Patent specifications are intended to be read and understood by a person with a good technical understanding of the field of the invention.  The legal terminology used to describe the intended reader is a “person of skill in the art”, or simply a “skilled person”.  This hypothetical person has a good understanding of the technical background of the invention and would understand key terminology and practices used in the field. 

Patent specifications are usually split into the following parts which are described in more detail below:

  • Abstract
  • Background
  • Summary of the invention
  • Detailed description of the invention
  • Claims
  • Figures



Most countries require patent applications to have an Abstract which summarises the invention.  It is mainly used for patent searching purposes and is published with the application’s bibliographical information on the respective office’s patent search website.  If applicable, abstracts also include a chemical formula relevant to the invention.


The background outlines the field of technology into which the invention falls and describes the state of the art before the patent filing date.  This body of knowledge and literature is referred to as the “prior art”.  Typically the background also notes the limitations or problems with current technologies.  This sets the scene for the new invention to solve the problems identified.

Summary of the invention

This section includes statements which set out the key features of the invention which the inventor believes are novel and inventive over the prior art.  Each different embodiment (example) of the invention should be identified in this section.  If the invention is a combination of steps of a method, or features in a particular configuration, these combinations/configurations should be specifically defined.

The statements in this section typically mirror the wording of the claims.  Since the patent claims define exactly what must be done to infringe the patent, they must contain clear, unambiguous language.  If there are words used in the Summary of the invention which would be ambiguous when read by the skilled person, those words should be defined in the Detailed description of the invention.   

Detailed description of the invention section

The detailed description of the invention (or simply the description) includes a detailed discussion of the features of the invention and how it would be made and used.  It should also contain definitions of any terms used in the specification that may be ambiguous to a skilled person.  The description often continues the narrative from the background.  For example it may state how the invention solves the problems previously identified, or list benefits of the invention over the prior art. 

As an example take a new chemical compound for repelling mosquitos.  The description should include details of the compound itself and any isomers, salts etc.  Information on how the compound is made, stored and used should also be included.    

It is important to describe alternatives and variations of features so that a broader claim scope can be justified.  For example, where functional groups could be substituted without affecting the core functionality of the compound as a repellent, these functional groups should be identified and details of optional substituents provided. 

Working examples of the invention are also typically included within the description.  Examples demonstrate to the reader that the invention has been made and works as a mosquito repellent as promised.  Patent examiners may only grant a patent if scientific evidence supporting the invention is presented in the specification. 

For our mosquito repellent, the examples may provide synthesis routes and analytical data identifying the compound and its structure.  Experimental data may also be included showing behavioural aversion to the compound by mosquitos.  Data may be provided for different mosquito species to show that the compound is not species-specific.  It is important to note that the data and experimental work does not need to be to a peer review level with a high degree of statistical significance.  However, it does need to be sufficient to show that the invention works. 


The claims are the key part of the specification because they define exactly what a person must do to infringe the patent.  In this way, they define the scope of the patent itself. 

The claims are a list of numbered statements found after the description.  They consist of a preamble and one or more features which outline the novel and inventive features of the invention.  For chemical compound inventions it is allowable to include the chemical structure in the claim itself and define the functional groups of the formula. 

For example, a claim to a novel mosquito repellent may read as follows:

  1. A compound of formula I:

  • where X is selected from methyl, ethyl or propyl.


In this case, the preamble of the claim is a “compound”.  This imparts to the reader an understanding of the type of invention that is being claimed.  Patent claims may have any preamble but it should be a clearly understood term that effectively categorises the invention.  For example, some common preambles include a product, a process, a use, a composition.  

The features of this claim are the formula and the definition of X.  To be allowable, these features must be novel and inventive over the prior art. 

To infringe this claim (and therefore the granted patent itself), a third party must make, use, sell or import the compound into the country where the patent is granted.   


The figures show graphical representations of the invention (or parts of it), or data which supports the invention (e.g. graphs or modelling data).  The figures usually appear at the end of the specification and generally include alphanumeric reference labels which are referred to in the description. 

It is important to note that the figures only show examples of the invention and should not be relied on to assess the scope of protection.  It is the claims that define the extent of the monopoly.   


Understanding patent specifications is an important skill for any researcher or technology manager.  This primer gives a basic overview of a complex and constantly evolving topic to enable you to read and make sense of patent specifications relevant to your field of technology.

If you have any queries regarding intellectual property related matters (including patents, trademarks, copyright or licensing), please contact Tim Stirrup.


This article is intended to summarise potentially complicated legal issues, and is not intended to be a substitute for individual legal advice. If you would like further information, please contact a Baldwins representative.

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