In the case 2 U 42/20, the Düsseldorf Higher Regional Court dealt with the equivalent patent infringement of a stripper unit for a stamp holder.

An equivalent patent infringement, i.e. a patent infringement of a patent claim of a granted patent by a product which is modified in comparison to the patent claim by at least one substitute means, requires the fulfillment of three criteria according to the established case law of the German Federal Supreme Court. The first two criteria are the technical equivalence of the substitute means and the obviousness of the substitute means to the average person skilled in the art.

The third criterion is the orientation of the skilled person to the patent claim when searching for the replacement means. In other words, the third criterion requires that the skilled person's considerations be guided by the patent claim, to which the patentee is bound. Thus, it is not sufficient that the person skilled in the art recognizes the variation as technically useful and having the same effect of the teaching of the patent claim.

In its reasons for judgment of April 8, 2021, the Düsseldorf Higher Regional Court further substantiated this third criterion beyond the case law already existing on the third criterion. For the third criterion, a distinction has to be made between such features in the patent claim which, from the point of view of the person skilled in the art, are representative of a certain technical principle of operation and such features which can only be implemented at all in a way corresponding to the literal sense, because any deviation would be diametrically opposed to the technical teaching of the patent in suit. Only in the first case an equivalent patent infringement is possible at all.