In order to meet the requirements of Article 83 EPC, a European patent application must contain sufficient information to allow a person skilled in the art, using his common general knowledge, to perceive the technical teaching inherent in the claimed invention and to put it into effect accordingly. In other words, the disclosure of the invention must be reproducible without undue burden,Decision of 24 June 2008, reasons 2.2, ".. according to the well established case law of the Boards of Appeal.. the disclosure must be reproducible without undue burden." See also "Reproducibility without undue burden". and this must be true over the whole scope of the claim. This requirement must be complied with as from the date of filing because a deficiency in a European patent application as filed, consisting in an insufficient identification of the subject-matter claimed, cannot subsequently be cured without offending against Article 123 EPC which provides that the subject-matter content of a European patent application as filed may not be extended. An insufficiently clear and complete disclosure of the invention is a ground of opposition, and revocation.
The burden of proof generally lies upon an opponent to establish insufficiency of disclosure.Decision of 24 June 2008, headnote. However, "when the patent does not give any information of how a feature of the invention can be put into practice" and if the opponent plausibly argues that "common general knowledge would not enable the skilled person to put this feature into practice", the burden of proof can be shifted to the patentee to show that "common general knowledge would indeed enable the skilled person to carry out the invention."
Relationship between Articles 83 and 84 EPC
Depending upon the circumstances, an ambiguity in the claims may very well lead to an insufficiency objection., Reasons 2.5.2. As held in decision T 608/07 of 27 April 2009, That a lack of clarity in the claims may, in some cases, result in an insufficient disclosure of the invention has been also pointed out by Board 3.2.05 in decision T 1811/13 of 8 November 2016. The Board explained however that:
specifies the content of the description of a European patent application and constitutes an implementing rule of Article 83 EPC. Rule 42 EPC notably specifies that " description shall... describe in detail at least one way of carrying out the invention claimed, using examples where appropriate and referring to the drawings, if any." In that respect,