10.2.2 Isolated examples of prejudice

Generally speaking, prejudice cannot be demonstrated by a statement in a single patent specification (T 19/81, OJ 1982, 51; T 392/88, T 900/95, T 1212/01), since the technical information in a patent specification or a scientific article might be based on special premises or on the personal view of the author. However, this principle does not apply to explanations in a standard work or textbook representing common expert knowledge in the field concerned (T 321/87; T 392/88; T 515/91; T 453/92; T 1212/01).

In T 943/92 the existence of a prejudice was supported by a specialist book which reflected the technical knowledge in the special field of the contested patent. This book did not contain the opinion of just one specialist author, but that of experts in the field, as it had resulted from the collaboration of "numerous recognised scientists, technicians and practicians as well as associations and institutes". General critical remarks in one textbook were not sufficient to substantiate an alleged prejudice, if a plurality of prior art documents pointed to the opposite (T 134/93).

In T 1989/08 the board noted it was not enough that the opinion or idea was held by a limited number of individuals or that it was a prevalent view within a given firm, however large. In the case in hand all the evidence offered in support of the alleged prejudice amounted to no more than ten documents, all of which were either specialist papers or patents. This small number of publications intended for a select readership in the field was in itself a tenuous basis for asserting prejudice (see also T 25/09).

In T 2044/09 the board did not interpret a declaration by a technical expert in the field as evidence that there was a prejudice in the prior art at the priority date; rather, this declaration was taken as the opinion of one expert, issued almost ten years after the priority date.

In T 638/19 the board found that regarding the alleged prejudice in the prior art, D4 and D1 were isolated publications which neither constituted common general knowledge nor presented conclusions that could be understood by the skilled person as being generally applicable. Therefore, they could not set a prejudice for the skilled person.