Cheaper Patenting: Writing Your Patent Specification

Part of a series teaching you how to reduce patenting costs.

OK. You’ve done a search and nothing appears to anticipate your idea.  You’ve got the green light to proceed with a patent application. What do you do?

You now need to prepare a patent specification. This will be the document that is filed at a national patent office to begin the process of obtaining a patent. The process of writing a patent specification is referred to as “drafting”.

As your legal rights are defined by the contents of the patent specification, in particular a section at the end of the specification called the “claims”, it is vital that the specification is properly prepared. Having seen a number of inventor-written patent specifications, I strongly recommend involving a patent attorney, if only to make sure the claims are well-drafted. This is because you need to have spent thousands of hours writing, revising and amending claims as well as understanding the law in at least one jurisdiction to properly draft claims; it is unlikely that most inventors will be in this position. Many inventor-written patent specifications are rejected during examination, wasting hundreds or thousands of pounds in official fees.

So if you need to hire a patent attorney to write at least a portion of your patent specification, how can you minimise his/her costs?

What is a Patent Specification?

In brief, a legal document usually consisting of around 20-40 pages of written text and a number of drawings or figures. It will be written in a number of iterations with the inventor. It has some similarities with a high-level standards document.

The written text consists of the following sections:

  • “Field of Invention” – This is a short paragraph – three or four sentences – which sets out the field of technology of the described invention. It generally mirrors the wording of the beginning of the main claim. The aim of this section is to guide a person searching for related documents; it may mirror the hierarchies expressed in one or more patent classifications. For example, if your invention is a new form of turbine blade for a wind turbine, the “Field of Invention” may be something along the lines of: “The present invention relates to turbines. In particular, but not exclusively, the present invention relates to a turbine blade and a method of constructing such a blade. The present invention is particularly suited for employment in wind turbines“.
  • Background” – This provides the background to your invention. It is usually one or two pages. Like a good detective story, it should describe the problems faced by existing solutions without hinting at your own particular solution. It is worth keeping this reasonably broad and reasonably brief, what might seem to you, the inventor, to be an obvious problem might not be so obvious to a generic “skilled person” in your field of technology.
  • “Summary of Invention” – This section typically mirrors, or makes reference to, the claims of a patent specification. If the following detailed description does not explain the advantages of your invention, you may wish to add these here. You may also wish to briefly expand on important portions of the claim language. As the “Summary of Invention” may need to be updated as the language of the claims is changed during examination of the patent application, for European practice I typically recommend only referencing the independent claims (e.g. “An aspect of the present invention is set out in claim 1“) and describing any advantages and/or expanding on claim language in the detailed description.
  • Description of the Figures” – This section briefly describes the figures or drawings. A brief sentence is needed for each figure. For example, “Figure 5 is a circuit schematic showing an example of the present invention“.
  • “Detailed Description” – This is the meat of the patent specification. It describes, in detail, each implementation of your invention (referred to as “embodiments”). Typically, the description is based on the figures. The figures may show the structure of an implementation from one or more angles, a flow chart or schematic illustrating a method of manufacture and a flow chart or schematic illustrating a use of the invention. Hence, the description may describe a structure, a method of manufacture and a use of one or more implementations. The figures may illustrate a hierarchy of abstraction – a feature may be illustrated in one figure at a systems level (e.g. a functional box) and in another figure at a detailed level (e.g. a circuit or engineering diagram). Any variation you can think of should be described. The detailed description should present your idea as a non-obvious solution to any problems described in the “Background”. The detail description should describe the general idea as well as the detailed implementations. The detailed description needs to support any claims (enable a general practitioner to replicate or create any product or process defined in the claims).
  • “Claims” – These are a number of paragraphs that set the scope of legal protection, i.e. any monopoly granted by an eventual patent.  They are the most important part of any patent specification. They are numbered. Claim 1 is what is called an independent claim – it does not refer to (i.e. include) the features of any other claim. Claim 1 cannot be anticipated by, nor rendered obvious in light of, any document published before the patent application is filed. However, it should also be broad enough to cover any immaterial modifications (“work arounds”). More features will be typically added to claim 1 during examination of the patent application as published documents relating to your idea are found. Dependent claims refer to other claims and include all of their material, e.g. if claim 1 specified feature A and claim 2 referred to the invention of claim 1 with feature B, claim 2 requires features A and B.

If you bear these sections in mind when providing information about your idea this can save time in drafting and hence save costs.

How Can I Help?

In most cases, the more information an inventor or company provides about an idea the better. The following tips should help reduce drafting costs:

  • The inventor is primarily responsible for the text of the Background and the Detailed Description and the Figures. He/she should concentrate on providing this. A patent attorney can quickly write the Field of Invention, the Summary of the Invention and the Description of the Drawings once this has been supplied and the claims have been drafted.
  • Figures are hugely helpful when drafting. Hand-sketched or computer-generated documents are fine. Flow diagrams and system diagrams are perfect. Editable engineering or network diagrams in a CAD or Visio format are also great. Don’t worry about cleaning these up too much, they will usually need to be edited as part of the drafting process. For example, a large engineering diagram may be broken up into several smaller cutaways. It is also useful to supply any drawings early in the drafting process. A usual number is 5 to 10.
  • For the Claims the most useful input is a series of keywords that the inventor believes covers the invention. It is also useful to indicate any features that he/she believes are essential (i.e. without which the idea will not work or will not have its effect). For the dependent claims, the inventor could attempt to identify any non-essential variations, modifications or specific implementations that have independent (non-obvious) advantages. For example, if claim 1 specifies a “biasing mechanism” but in one implementation a compressible rubber bung is particularly useful as it is easier to mould into a particular configuration then claim 2 could specify this bung.
  • A complete list of acronyms used in any text is useful. Those in a specialised field may not be aware of other abbreviations but a quick look at any Wikipedia disambiguation page shows how ambiguous some acronyms can be. This is especially important in technical fields with their own jargon (e.g. oil speculation, telecommunications etc.).
  • It is helpful if the inventor provides at least three different implementations of his/her idea, even if only one of them may find its way into a product. This is because designs often change during the product lifecycle and a patent specification has to take this into account. The claims should thus cover any changes that can be made which do not affect the underlying technical idea. Three different implementations helps provide basis, i.e. legal support, for any generalisations to accommodate changes. For example, an electronic device may have a display. Over a product lifecycle that display may be implemented by a LED array, a CRT screen and then by an AMOLED panel. Hence, the claims need to specify a display rather than any of the particular implementations. In any description the inventor may say “At the moment we use a LED array but ant display could be used including a projected image or an LCD panel.
  • As well as a description of a structure, a description of use and manufacture is also important. It may not always be obvious to provide this, especially when the inventor may consider it easy to infer these details from the structure. A good idea is to imagine a patent attorney as a well-meaning yet simple teenager; if you have a good attorney they will not be insulted (remember a judge’s or jury’s science education may only be at a high-school or GCSE level). The patent attorney can chose the appropriate level at which to provide the technical detail in the specification.
  • Review any documents provided by a patent attorney in detail and answer any questions in full.
  • Provide any supporting documents that may be relevant to the background of your idea. For example, old manuals, text book entries or old scientific papers. A useful tip is to dig out a shortlist of between 10 to 20 documents then provide the most relevant and informative 5.
  • Make use of change tracking software, such as “Track Changes”, and make your attorney use it too. This saves a lot of time when performing iterations of the text. In-line comments are also handy.
  • If anything does not appear clear or the language seems strange point it out to the drafting attorney. It some cases it may be a quirk of “patentese”, the language of patent attorneys; in many cases, it will get the attorney thinking and improving the specification.


For a patent specification to have any chance of passing examination, and being held up as valid in court, it does need to be drafted by a patent attorney. However, there are many steps an inventor or company can take to minimise the drafting time and thus minimise the drafting costs.

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