How sufficiency of disclosure is assessed
 Insufficiency of disclosure


An invention is sufficiently disclosed in the application if a person skilled in the art is able to put it into practice on the basis of the application.

The level of detail must be sufficient for the skilled person to understand the contribution to the prior art and to learn how the invention works and can be put into practice. It may be sufficient to provide an example of how it can be put into practice. In other words, the description must provide an enabling disclosure of the invention.

Person skilled in the art
The person skilled in the art is an average expert/experienced practitioner with average knowledge and ability in the particular technical field of the invention, but no inventive ability. They should also be presumed to have had access to everything in the state of the art and to have had at their disposal the normal means and capacity for routine work and experimentation.

European Patent Convention
Article 83 EPC: Disclosure of the invention




Rule 42(1)(e) EPC requires the application to describe in detail at least one way of carrying out the invention. The applicant must therefore make sure that the invention is described in a way that allows a person skilled in the art to reproduce it.

European Patent Convention
Rule 42 EPC: Content of the description

This means that, even if the application does not provide all of the necessary details, the examiner is able to work out the missing information on the basis of the application as a whole using their common general knowledge in the field.

If this is not the case, the examiner may conclude that there is a serious lack of sufficiency of disclosure in the application. This can happen when:

  • The successful performance of the invention is based on chance, i.e. the alleged results cannot be repeated, or the success of the invention is unreliable (e.g. microbiological processes involving mutations)
  • The successful performance of the invention is inherently impossible, i.e. because this is contrary to well-established physical laws (e.g. a perpetual motion machine)




If the application is found to contain lack of sufficiency of disclosure, the reasoning provided by the examiner must explain why the person skilled in the art, using the information provided in the application and their common general knowledge, would not be able to perform the invention over the whole area claimed without undue burden and without needing inventive skill. The reasoning must be based on verifiable facts. For example, the examiner could refer to a particular example covered by the claim.

The finding that an invention is not sufficiently disclosed can have particularly severe implications for the application, because a fundamental deficiency of disclosure cannot usually be overcome.

If the invention is found to be insufficiently disclosed, it is the applicant’s responsibility to establish that it can be performed and repeated substantially over the entire claimed range. In addition, if there are serious doubts about whether the invention can be performed and repeated as described, it is up to the applicant (or proprietor) to at least demonstrate that its success is credible.


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