1.13.3 Negative features

In T 170/87 (OJ 1989, 441) the board held that a figure which served only to give a schematic explanation of the principle of the subject-matter of the patent and not to represent it in every detail did not allow the sure conclusion to be drawn that the disclosed teaching purposively excluded a feature not represented. Such a "negative" feature (in this case, "with no internal fittings") could not subsequently be incorporated into the claim (see also T 410/91, T 1120/05, T 474/15 and T 621/15). Regarding the absence of a feature in a figure which served only to give a schematic explanation of the principle of the invention, see also T 264/99, in which the board found the circumstances to be different from those in T 170/87.

In T 1120/05 the invention concerned an "arrangement for and a method of managing a herd of freely walking animals" and the amendment introduced a negative feature namely "but not to the milking station". This negative feature was not expressly disclosed in the description and in the claims of the patent application as filed. Features could be taken from the drawings if their structure and function were clearly, unmistakably and fully derivable from the drawings. It was not possible to derive a negative or missing feature on its own, i.e. without the context of the other, existing features of the claim. Moreover, arbitrarily choosing one of many possible negative features was not permitted (see also T 777/07), because the skilled person not only had to realise the possible negative features, but – because they were derived from the drawings – he also had to establish which one of the features was essential to the invention and which ones were not. The board found that in the absence of a teaching from the description, the skilled person would be unable to establish the essential nature of a single negative feature, seen against a background of a multitude of potentially essential features, even if this selected single negative feature in the drawings could be recognised by the skilled person in the drawings.