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Experimental data in a European patent application: how much is enough?

rachel-mercerIt is not unusual for an inventor or applicant to ask: “How much experimental data do I need to file a patent application?” Interestingly, the European Patent Office (EPO) does not require that a patent application contains any experimental data or results. However, in most instances, experimental data will be an important aspect of the application, for meeting the requirements of Articles 83 and 56 EPC (sufficiency and inventive step).

Sufficiency of disclosure requires that the teaching of the application as a whole, including examples, allows the skilled person to carry out the invention over the whole scope of the claims, without undue burden. At least one way of carrying out the invention must be disclosed (by way of experimental data, for example). However, one example may not be enough if the claims are drafted very broadly, since the application must enable the skilled person to perform the application over the whole scope of the claim. Consequently, if claims are drafted broadly with a view to obtaining a broad scope of protection, applicants should seek to include experimental data covering the whole breadth of the claim.

In order for a patent to be granted for an invention, the invention must involve an inventive step. The EPO assesses the presence of inventive step using the problem and solution approach in which an objective technical problem is formulated based on technical effects of the invention which are not achieved in the closest prior art. If a technical effect is not rendered plausible by the patent application as filed, that technical effect cannot be considered in the assessment of inventive step.

Although experimental data is not always required in order to demonstrate a technical effect, in EPO Board of Appeal case T488/16, which related to the revocation of a European patent directed towards the drug dasatinib, the Board noted that if the technical effect on which the application relies is neither self-evident nor predictable based on a conclusive theoretical concept, at least some technical evidence will be required. In biotech applications, which often rely on an unexpected technical effect, a statement simply asserting the presence of a technical effect is unlikely to be considered enough to render a technical effect plausible. Therefore, applicants in this field should seek to include evidence in the application as filed that demonstrates that a particular technical effect is achieved. Although additional data supporting the presence of an inventive step can be filed at the EPO during prosecution of an application, such data can only be used to support a technical effect which was made plausible from the application as filed. It is therefore essential that such plausibility is established prior to filing an application.

The question of how much data to include in an application is a delicate balancing act - on the one hand, the desire to include as much experimental data in the application as possible to ensure that the criteria of sufficiency and inventive step are met, and on the other, the need to file an application as soon as possible to secure the earliest possible priority date. In general, we would suggest including as much data as possible which supports the invention over the whole scope of the claims. If a limited amount of supporting data is available, one option is to file an initial application with the available data and during the twelve months following filing, obtain additional data supporting the invention. Such additional data could be introduced in further applications filed within twelve months of the initial filing which can claim priority back to the original application. However, if no evidence establishing sufficiency and demonstrating a plausible technical effect is available it may be beneficial to delay the initial filing until at least some evidence is obtained, as it may not be possible to rectify such an omission with additional data at a later date.

Rachel Mercer is a Patent Attorney at Appleyard Lees.


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Rachel Mercer
Written By
Appleyard Lees is a long-established intellectual property firm, with a multidisciplinary team of patent and trade mark attorneys. From a network of offices, we provide Intellectual Property (IP) services to the whole of the UK, Europe and the rest of the world. We are committed to delivering our highest service levels at the right cost. We have an experienced and dedicated team with specialist knowledge in technical areas including headline sectors such as Electronics & Software, Engineering & Physics, Chemistry & Pharmaceuticals and Life Sciences & Biotechnology. 

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