1.4.3 Omission of a feature presented as essential

For cases in which the amendment consists of the replacement or removal of a feature from an independent claim, the boards occasionally apply the test of decision T 260/85 (OJ 1989, 105). In T 260/85 it was stated that it was not permissible to delete from an independent claim a feature which the application as originally filed consistently presented as being an essential feature of the invention, since this would constitute a breach of Art. 123(2) EPC 1973. See also T 496/90, T 415/91, T 628/91, T 189/94, T 1032/96 (segment length parameters explained as essential), T 728/98 (OJ 2001, 319; concerning the deletion of the feature "substantially pure"), T 1040/98 (acoustic waveguide is described in the form of a bladder filled with a suitable material, throughout the description), T 1390/15 (consistent disclosure of solubility limit on the content of Mg and Cu), T 1515/11 (feature explicitly defining that the method was carried out in a manner which solved the problem) and T 1187/15 (consistent disclosure that heart rate can be derived from the blood pressure measurement). For recent decisions following this approach, see T 1099/21 and T 897/20.

In T 236/95 the board held that if the problem could not be solved without the features concerned, they could not be considered unimportant.

In T 784/97 the patent proprietor alleged that a prior art document would have made the skilled person aware that the disputed feature was not essential. The board held that whether or not a feature of an independent claim had to be seen as "essential" could not be a question of the prior art disclosure. Rather, what had to be decided was what a skilled person was taught by the originally filed documents.

The board in T 648/10 confirmed the test set out in T 260/85. However, it observed that the EPC does not require the use of any particular tests when assessing whether subject-matter has been added. Instead, such tests are tools which may be helpful, in certain situations, in the assessment of whether subject-matter has been added.