In a recently published decision (1), the German Federal Court of Justice (BGH) once again addressed the issue of the role of the knowledge of a person skilled in the art in the assessment of inventive step. This provides an opportunity to examine this question specifically in connection with biotechnological inventions.

The mother of all decisions

An equally important and often frustrating experience is that the knowledge of the skilled person is sometimes viewed completely differently by the European Patent Office on the one hand and the DPA and the German courts on the other. A bon mot is that the European skilled person has difficulties peeling a banana, while its German counterpart can conclude from its angle of curvature where the fruit comes from. In fact, the situation regularly arises in which a patent survives the European opposition appeal proceedings unharmed, but is revoked in the German nullity proceedings without a care in the world – and this with the same document situation.

The question of whether technical knowledge is suitable for establishing the obviousness of a technical teaching when this is expressly not suggested by the printed prior art is the subject of the landmark decision „Paint Supply System“ (2) from 2014, which sets out three test criteria, all of which must be met for technical knowledge to replace missing prior art:

1. The corresponding feature must be familiar to the skilled person as a general means. This is the case, for example, if it is common textbook knowledge.

2. The feature must be objectively appropriate to solve the problem. In the specific case, it was a question of a device being designed in such a way that it could carry out two operations in parallel, instead of only one at a time as disclosed in the prior art.

3. The realization of the feature must not be associated with particular difficulties. This includes objective disadvantages in its use, especially if the prior art also specifically advises against it.

This methodology can also be found in a similar form in the examination for equivalence in patent infringement („cutting knife questions“).

Significance for biotechnological inventions

The BGH emphasizes that although the individual case is decisive in assessing the knowledge of the person skilled in the art, the same standards must always be applied. It remains to be seen to what extent this is at all possible in technological areas such as RNA technology or genome editing, in which there is an enormous increase in knowledge practically every day.

In the „Antibody Detection“ (3) decision, the BGH at any rate denied the application of technical knowledge as a substitute for a printed publication as the closest state of the art. The specific case concerned the detection of antibodies in a sample, in which a „reverse sandwich“ was used. For detection, a „fishhook“ was laid out in the form of an antigen to which the antibodies – if present – could dock. Detection was then achieved by docking a second antigen. In this way, a complex of antigen-antibody-antigen was formed – the „sandwich“. It was undisputed that the use of reverse sandwich structures represents textbook knowledge. The novelty arose from the fact that, in this context, there was previously only very general talk of „ligands“ that dock onto the complex of antigen and antibody. However, the fact that antigens can also be used for this purpose was unknown.

In the invalidity proceedings, the plaintiff had therefore argued that the technology was undoubtedly known to the person skilled in the art as a suitable tool and that there could be as little doubt as to its usefulness as to the fact that no serious difficulties had to be overcome in order to achieve it.

The BGH did not agree with this. Although the accessibility and expediency of the substitution means were not in question, it had been pointed out in the textbook that the suitability of certain ligands depended on the respective purpose of use. This was considered by the Senate to be a technical peculiarity which did not make the application of the technical knowledge mandatory.

Teaching to act

It can be assumed that the „antibody detection“ decision would have turned out differently if the textbook had not mentioned that the selection of ligands is purpose-dependent. One may even assume that the specific selection of antigens as ligands would have been regarded as familiar to the person skilled in the art, without the need for a citation in print.

For the practitioner, the case law means that it is possible in German nullity proceedings, even without sufficient disclosure in the form of prior written publications, to successfully challenge the inventive step of a granted patent, if one justifies this with the general knowledge of the person skilled in the art and shows that the criteria defined in „Color Supply System“ are fulfilled.

1) BGH X ZR 19/21 (31.01.2023) – „Staubsauger“

2) BGH X ZR 139/10 (11.03.2014) – „Farbversorgungssystem“

3) BGH X ZR 115/17 (27.03.2018) – „Antikörpernachweis“