EP Case Law in Brief: Proof of common general knowledge


It is a common sight for a patent attorney – an EPO Examiner acknowledges that a claim is novel, but asserts a lack of inventive step over ‘D1’ in combination with ‘common general knowledge’ (CGK). When considering the ability to challenge this assertion, section I.C. 2.8.5 of the Case Law of the Boards of Appeal provides some guidance.

General principles

It is well established in the case law (T 438/97, T 329/04, T 941/04, T 690/06, T 2132/16) that if the status of some information as CGK is challenged, the person asserting that it is CGK must provide proof, such as with documentary or oral evidence T 939/92). The Board of Appeal, for example in T 1540/14, has overturned the findings of an examining division, when no sufficient documentary evidence of CGK was provided.

In T 766/91, it was explained that such proof is only required if the status of CGK is challenged. An example of this being implemented was in ex parte case T 2101/12, where it was found that no documentary evidence was required because the appellant “has at no moment disputed that the process […] is indeed common general knowledge”.

No general obligation on the Boards of Appeal

Whilst this may be true in examination and opposition proceedings, in T 1090/12, an ex parte decision, the Appeal Board determined that the Board of Appeal itself does not have to act within these principles. The Board stated there was “no general obligation on a board to provide documentary evidence for the existence of a piece of common general knowledge.” It stated that because “its members knew from their work on previous cases that the features were known to the person skilled in the art”, it was “for the appellant to show an error in the board’s appreciation”. T 1370/15 confirmed that this principle held even for inter partes appeal proceedings, stating “A mere denial that such commonly known prior art existed is not sufficient.”

Date of documentary evidence

The Board of Appeal in T 1110/03 found that documentary evidence for CGK does not necessarily need to have been published before the priority date. They stated that these documents:

“do not stand or fall by their publication date even on issues of novelty and inventive step. Thus a dictionary is by definition an account of the meanings of words which existed prior to the publication date of the dictionary - sometimes centuries or even millennia earlier - which could bear on the issue of interpretation and hence novelty. Similarly a technical review article is by definition an account of the common general knowledge in the art prior to its own publication date - which could bear inter alia on the issue of enabling disclosure of a prepublished document and hence on the novelty of claimed subject-matter.”

This concept was also upheld in T 608/07, where D6 was university course material, published after the priority date of the patent. The Board held that the content was ”not the personal opinion of the lecturer but clearly relates to subject-matter well known in the art for many years”.

Appeal Board decision T 2196/15: A Cautionary Tale

Some of the difficulties of establishing the CGK of the skilled person can be seen in T 2196/15. In this decision, the Appeal Board found that the personal knowledge of a professor in the field of the invention could not “be used to establish what actually was the common general knowledge of the skilled person at the time”. The Board opined that the professor was “a highly qualified academic in the field” and his “knowledge and understanding of the matter clearly [went] far beyond what may be expected of the person skilled in the art, i.e. an experienced practitioner who has average knowledge and abilities”.

In the same decision, a scientific article was put forward as establishing the CGK. It was accepted, perhaps unusually, that such a scientific article could express the CGK of the skilled person because the field was so new that technical knowledge was not yet available in textbooks. However, the content of the article did not provide enough evidence that the feature contested was CGK. A series of other documents, including slides presented at a conference, were also discussed, but were concluded to be unsuitable for establishing the CGK.

The respondents in T 2196/15 filed two declarations in order to show that a feature was not part of the CGK. However, the Board stated that the “intrinsic weakness of such declarations consists in the fact that absence of common knowledge is difficult to prove on the basis of individual cases.” Nevertheless, the Board said that such evidence is not irrelevant; one of the declarations was from someone working in product development at the priority date, who was said to have been “in a situation closer to the (fictitional [sic]) average skilled person” than the professor mentioned above. Therefore, “his assertion that he did not possess the relevant knowledge at that time constitutes an element of evidence that should not be ignored.”

In this case, the Board concluded that the purported CGK was not established.