T 0021/81 (Electromagnetically operated switch) of 10.09.1982

1. If, having regard to the state of the art, something falling within the terms of a claim would have been obvious to a person skilled in the art, because the combined teaching of the prior art documents could be expected to produce an advantageous effect, such claim lacks inventive step, regardless of the fact that an extra effect (possibly unforeseen) is obtained.

2. It has to be considered as forming part of the normal activities of the person skilled in the art to select from the materials which are known to him as suitable for a certain purpose the most appropriate one, and this also in the case where he is presented with no more than an unreasoned preference for a specific material in a document forming part of the prior art.