Part 2: Supporting the Invention

Part 3: Amendments at the EPO

As those familiar with the patent process will know, a European patent is obtained via the European Patent Office (EPO).  In order to get a European patent granted, it has to meet a series of requirements set by the European Patent Convention (EPC).  At least in some respects, the EPC’s requirements are considered stricter than for many other jurisdictions, and patent applications drafted and prosecuted without an eye on its quirks can often run into trouble – sometimes fatal trouble.

The patenting process is collaborative.  A good invention may fall short of a patent if poorly drafted and prosecuted.  Likewise, even a great patent attorney will struggle to make a silk purse from a sow’s ear.  So how can a patentee get the patent monopoly they want in Europe? Our attorneys at Gill Jennings & Every have extensive experience of handling applications in the chemical field during examination, as well as in opposition and appeal proceedings before the EPO.  Across a three-part series, we look at how our experience can help in the preparation of your patent applications, and how to avoid the pitfalls of the EPC.

Consider clarity and sufficiency before filing

Chemical inventions by their very nature can be difficult to define clearly, which is all the more reason for patentees to consider this carefully before filing a patent application to ensure it meets the EPO’s standards.  One of the first formal assessments of a patent application is to question whether the claims, which define the scope of patent protection, are clear, such that they can be easily understood by the reader.

A European patent application must also disclose an invention in sufficient detail for it to be performed across the scope of the claims.  Although strictly speaking this requirement (“sufficiency”) is a separate legal requirement to clarity, in reality, the two requirements can overlap.  For example, an invention may be so poorly defined that the lack of clarity can lead to the patent application falling foul of the sufficiency requirement.  It is advisable that patentees consider these issues fully before filing in order to ensure their patent applications are as water-tight as possible.  After all, it is not possible to add information to the patent application once it has been filed – all of the fall-backs, definitions and support must be present at the filing date.

Define the exact boundaries of the claim

The EPO has a “hard-edge” approach to clarity to ensure that the boundaries of a patentee’s monopoly are precisely defined.  This is so the public knows where they can and cannot tread.  A good example is the term “room temperature”, which is often seen in chemical patents.  This is a well-known term with a generally understood meaning.  However, an EPO clarity problem arises because there is no universally accepted definition of the exact temperature this term is referring to, and so the term does not provide a clear “hard-edge”.  Open-ended terms with no defined limits such as “substantially free” and relative terms such as “high melting point” suffer similar problems.  It is important that a European patent application at least includes a “hard-edged” definition of any potentially unclear term.  Good technical input is key to ensuring these definitions are as clear and unambiguous as possible.

Consider the risks and rewards of parameters in a claim

It is common, and sometimes advantageous, for chemical patents to define an invention functionally or by way of a parameter, rather than a purely “structural” definition.  Defining a composition by its viscosity or a polymer by its molecular weight could be more valuable, as the patent cannot be worked around as easily.  However, care needs to be taken to ensure that European patent applications contain sufficient information to make it clear what the parameter is defining, how to measure it, and how to achieve it.

It will be appreciated that an unusual parameter not commonly used in the field will require a thorough definition – but European patent applications can still fall down through the use of very common parameters that have not been defined with sufficient precision.  For example, the parameter “average particle size” may not cause any issues with some patent offices, but the EPO considers this term to be unclear.  The reason being, there are several different types of averages (such as the mean or median, by weight or by volume, etc.) which will likely take different numerical values.  All parameters, whether common or more unusual, therefore need to be defined with sufficient specificity so as to provide the required line in the sand.

Linked to this sufficient specificity is the measurement technique.  A patentee may think that if it is well known in the field how to measure a particular parameter, then there is no need to explain this in the patent application.  However, it is often the case that chemical parameters can be measured in more than one way.  What if these methods give different results? What if the value of the measurement depends on the conditions under which it is taken? The edges of the claims are now blurry and the patentee faces an uphill battle to convince the EPO that the definition of the invention is clear – an issue that often proves fatal.  It is strongly advised to ensure that any parameter that is, or might be, used to define the invention is supported in the application by a complete and unambiguous description of the apparatus, method, and conditions used to measure it.

Finally, where an invention is defined using a parameter, it is important that this definition is accompanied by sufficient information to allow the parameter to be obtained across the whole area claimed without an undue burden.  This is to avoid the EPO objection of a “result to be achieved” – that is, where the application essentially amounts to claiming all solutions to a particular problem.  An example of this would be an invention seeking to improve a particular property of a product, where the patent application uses a parameter to claim essentially all products having the desired property.  If products meeting a particular parameter can only be found by random trial and error, then this claim is likely to amount to an undue burden and may therefore receive an objection from the EPO.

Now that you have a clearly defined set of claims, and a well-supported patent specification, you need to make sure it is suitably robust for the rigours of substantive examination – the comparison with everything that was publicly available at your filing date, AKA the “state of the art”.  We will look at what kind of evidence and data are required to ensure that your patent will be considered inventive in our next instalment in this series.

Please do get in touch if you have any questions concerning the protection of your chemical patents.  Find our contact details on our website profiles here and here or contact us at