10.2.1 Demonstrating prejudice

Generally speaking, established board of appeal case law is very strict when it comes to recognising the existence of a prejudice. For a prejudice to be considered actually to exist, there must be a prevailing but incorrect school of thought widespread throughout the entire technical field. A solution put forward as overcoming a prejudice must clash with the prevailing teaching of experts in the field, i.e. their unanimous experience and notions, rather than merely cite its rejection by individual specialists or firms (T 531/95; see also T 62/82, T 410/87, T 500/88, T 74/90, T 793/97, T 2453/09). A high standard of proof to demonstrate prejudice is required; that the expression of the prejudice in standard works or a textbook is normally required, raises the level of proof close to that needed for proving common general knowledge (T 1989/08).

A typical way of proving a prejudice is the citation of common technical knowledge published before the priority date, although other ways cannot be excluded. However, statements in the patent that are not accompanied by the citation of specific evidence of the alleged prejudice are not a suitable way of demonstrating a prejudice. Similarly, a mere statement in a patent application, cannot prove the presence of a prejudice, either (T 2173/22).

In T 69/83 (OJ 1984, 357) the board held that the mere fact that the disadvantage resulting from the omission of a component of a mixture recognised in the art as advantageous was accepted suggested conscious acceptance of a disadvantage, not the overcoming of a prejudice. The fact that a disadvantage is accepted or the prejudice simply ignored does not mean that a prejudice has been overcome (see also T 262/87; T 862/91).

In T 347/92 the board pointed out that the finding of a relatively small operating window in an area which, according to the teaching of the most recent publications, was considered inaccessible, could not be considered obvious to a person skilled in the art.

In T 550/97 the board did not consider the fact that arguably less advanced solutions had been developed later, to be evidence of inventive step, as there was no reason to assume that later development was attributable to a technical prejudice which the invention had needed to overcome.

In T 1212/01 the patentee referred to some thirty scientific articles in order to demonstrate the existence of a technical prejudice that drugs lowering blood pressure were a cause of impotence rather than a form of treatment for that condition. The board, however, stated that the contents of such a selection from the prior art could not be considered per se as creating a technical prejudice against oral treatment of male erectile dysfunction. Such a prejudice could only be established by proving that, in relation to the technical solution, a relatively widespread error or misapprehension about the technical invention existed among skilled workers in the relevant field before the priority date of the patent in suit. This was not the situation in the case in hand.

In T 984/15 the board found that the fact that something was not explicitly disclosed, or even that it was explicitly prohibited, in a technical specification must not be necessarily interpreted as a prejudice of technical nature. There might be other non-technical reasons, such as circumventing a patented technology or simply lack of time in the meetings for further discussions that led the drafting group to dismiss or ignore an otherwise valid technical option.

In T 179/18 the board considered that the three years separating the filing date of the patent and the filing date of the disclosed prior art was not a long period indicative of a technical prejudice.