How to Read a Patent Claim - gauging your claims and others'
Patent Claims are the part of a patent specification that defines the scope of a patent. If you wish to determine what a patent covers, and what it does not, you need to look at the claims.
Quite often, it is useful for patent applicants and business people to be able to perform their own preliminary assessment of patent claims. This is useful as a gauge of whether something is worth pursuing further, as opposed to being the basis for making important decisions – something for which the expertise of your patent attorney is advised.
While fully interpreting patent claims is a learned skill best performed by experts, being able to assess a patent claim to obtain an indication of its scope can be easily learned. The following notes provide an outline to enable the lay person to appreciate the content of patent claims.
Where do I find the patent claims?
The patent claims are found at the end of the written description in complete specifications. They are easily identified in that they are numbered sequentially, and generally preceded by a phrase such as “The Claims Defining the Invention Are”.
Some countries provide for the filing of provisional specifications prior to the filing of a complete specification. Provisional specifications do not contain claims, but often contain Statements of Invention after the introduction. These sometimes comprise paragraphs beginning with “According to one aspect of the invention …” While not claims, these Statements provide an indication of the essence of the invention which may be claimed in patent claims in the Complete Specification. If you have a provisional specification, check to see if a complete specification has been published or is available.
Be also aware that some countries publish complete specifications before acceptance. These contain unexamined patent claims, which represent the protection the applicant would like, as opposed to what protection they may ultimately get. Please be aware of this, and check with your legal counsel before making any important decisions.
What types of claims are there?
There are two main types of patent claims – independent, and dependent. Claim 1 is always an independent claim. However there may also be other independent claims. These are readily identified as they do not make reference to any other claim.
Independent claims are generally the broadest claims, and because of this are generally the claims you would look at first. The first step in any analysis is to identify the independent claims.
Dependent claims refer to other claims. They generally take the form “A widget as claimed in claim 1 …” though other formats exist. Typically they are narrower in scope than the independent claim to which they refer as they introduce new features to those defined in the independent claim.
A third and less common type of claim is the omnibus claim. This is a ‘catch-all’ type claim often in the format “A widget, substantially as described herein with reference to the drawings.” These are normally interpreted to be narrow in scope, and refer to articles substantially as shown in the drawings (or to methods substantially as described in specific examples).
Breaking down the claim
Once you have identified, firstly, the independent claims it is time to break them apart. All claims are, in reality, just a list of features or integers. At the simplest level, gauging whether a claim may be infringed is as simple as matching features between the article (or method) in question and the claims.
The first step is to create a list of all of the features identified in the claim. It pays to break this down into as small an integer as possible. For instance, taking the following claim as an example:
“1. A widget for coupling conduits and comprising an end coupling element connected to a hollow tube, the coupling element including a retractable inwardly directed protrusion.”
The list which we would prepare would be:
- a widget
- suitable for coupling conduits
- a coupling element
- positioned at the end (of)
- a tube
- the tube being hollow
- a retractable protrusion on the coupling
- the protrusion is inwardly directed
This takes every feature mentioned in the claim, in its simplest form, and creates a check list which we can now use for gauging its scope.
Gauging the scope of the broken down claim
The general principle is – for a claim to be infringed, each and every feature must be taken. There are exceptions to this, but for the exercise of merely assessing the general scope of a patent claim, we shall take the principle literally. Hence, we now have a checklist for assessing whether something infringes the claim.
If we have an article or method for comparison, we merely analyse the article (or method) using the list of claim features as a check-list, placing a tick next to each item in the list which the article or method for comparison has.
Interpreting your results
If your checklist (relating to a claim) has a tick next to every feature, then in every likelihood that claim is infringed. However, if you are basing important decisions on this then please seek legal advice from your attorney before proceeding. For the purpose of obtaining an indication however, this is an effective test.
If most of the items on the list have been ticked, but several have not, then it is possible that the claim is not infringed. If the features which have not been ticked appear to be important or essential features of the invention, this is a reasonable indication that the claim is not infringed. On the other hand, if the un-ticked features could be construed as minor or irrelevant features not important to the invention as a whole, the claim may still be infringed. A more detailed interpretation by an attorney would assess the content of the specification and how these features related to the invention – the result being a much more accurate answer.
As a general rule, the less the number of ticked items there are, then the less the likelihood of infringement. Accordingly this procedure can be a useful first assessment for gauging patent claims before contacting your attorney for further advice.
Analyse the other claims
If the analysis of the independent claims is promising, you should then continue to analyse the dependent claims. The same procedure is followed, though noting that a dependent claim includes all of the features of the other claim to which it refers, as well as features mentioned in the dependent claim itself. Hence, a dependent claim such as “A widget as claimed in claim 1 including …” will include all of the features of claim 1 as well as what is mentioned in the claim itself.
If a claim (say claim 4) refers to another claim (say claim 3) which in turn refers to another claim (such as claim 1) then the checklist will include all of the features of claim 1 plus claim 3 plus claim 4. This produces a much longer checklist, but with the advantage that it will be harder to infringe (and hence is narrower in scope because it has more criteria or features which must be met).
Assessing your own patent’s claims
If you are the patent applicant, then the claims of your specification will define the scope of the protection offered by your patent. Others, wishing to gauge if they infringe your patent claims, will perform the same type of test.
To assess the scope of your own claims, again identify the independent claims and prepare the checklist. Look at the list and remember that for infringement someone must produce something with every feature in that list. Now consider, is there anything that they could leave out which would still give them a commercially viable product or process? If they can, then the patent claim appears not to provide you with the protection you may need – this is something to discuss with your attorney. Please note that sometimes other factors may influence the breadth of a claim – a wider claim may offer more protection, but may not be novel because it includes known subject matter within its scope. Consequently, most claims are the broadest reasonable protection an applicant can obtain but which are not invalid because they include known material.
Summary of Steps
- identify if it is an accepted complete specification with the claims in their final form;
- identify the independent claims;
- prepare a checklist containing every feature, for each independent claim;
- take the article or method for comparison, and tick every feature on the checklist that it has;
- review how many features it lists, and gauge the importance of missing features (where there are only a few) to determine whether the claim is likely to be infringed;
- seek further advice from a patent attorney before making any important decisions.