485. Assessment of obviousness.

The modern practice in relation to the issue of inventive step is to identify a relatively small number of items of prior art and then to identify the differences between those core items of prior art and the alleged invention. The crucial question whether the difference between the inventive concept of the patent and the state of the art represents an obvious step is one on which expert evidence is essential1. The primary evidence is that of properly qualified expert witnesses2 who will say whether or not in their opinions the relevant step would have been obvious to the