2.4.2 Deletion of feature from description where claim remains unchanged

In T 142/05 the board found that, even where the wording of the granted claims was unamended and clear, the mere deletion from the description of an important desired property of the patented subject-matter led to an extension of the scope of protection which contravened Art. 123(3) EPC 1973 (this is different in the case of an optional, hence not important feature, see T 71/10). The board explained that, although the claims were the most important element in determining the extent of protection, the wording of the claims should not be seen as the sole relevant factor; instead, the description and drawings were to be used in interpreting the claims. From this, it followed that even if the wording of a claim was clear and unambiguous, i.e. where the scope of its literal meaning was clear, reference was still to be made to the description and claims. This could lead to a different interpretation of the claim, diverging from that obtained by considering only its literal meaning. Amendments to the description and drawings could modify the content of the claims and thereby extend the scope of protection according to Art. 69(1) EPC 1973, even where the wording of the claims was clear and remained unamended. In the board's view, the deletion in the case at issue had the effect of generalising the teaching of the patent. Art. 123(3) EPC 1973 had therefore been contravened.

This approach was confirmed in T 1360/13, which related to the deletion of drawings (see below chapter II.E.2.4.5).