‘Their primary function is to educate the court in the technology – they come as teachers, as makers of the mantle [i.e. of the person skilled in the art] for the court to don. For that purpose it does not matter whether they do or do not approximate to the skilled man. What matters is how good they are at explaining things.’ [52] To that I would add this: although it is inevitable that when an expert is asked what he would understand from a prior document's teaching he will give an answer as an individual, that answer is not as such all that helpful. What matters is what the notional skilled man would understand from the document. So it is not so much the expert's personal view but his reasons for that view – these the court can examine against the standard of the notional unimaginative skilled man. There is an analogy here with the well-known Bolam test for professional negligence – what matters is not what the individual expert witness says he personally would have done, but whether the conduct said to be negligent falls short of what a reasonable professional would have done. [53] Thus in weighing the views of rival experts as to what is taught or what is obvious from what is taught, a judge should be careful to distinguish his views on the experts as to whether they are good witnesses or good teachers – good at answering the questions asked and not others, not argumentative and so on, from the more fundamental reasons for their opinions. Ultimately it is the latter which matter – are they reasons which would be perceived by the skilled man? ‘Their primary function is to educate the court in the technology – they come as teachers, as makers of the mantle [i.e. of the person skilled in the art] for the court to don. For that purpose it does not matter whether they do or do not approximate to the skilled man. What matters is how good they are at explaining things.’
"In applying the statutory criterion [i.e. as to whether an alleged inventive step was obvious] and making these findings [i.e. as to obviousness] the court will almost invariably require the assistance of expert evidence. The primary evidence will be that of properly qualified expert witnesses who will say whether or not in their opinions the relevant step would have been obvious to a skilled man having regard to the state of the art." [14] But just because the opinion is admissible: "it by no means follows that the court must follow it. On its own (unless uncontested) it would be "a mere bit of empty rhetoric"
"The well known principle that patent claims are given a purposive construction does not mean that an integer can be treated as struck out if it does not appear to make any difference to the inventive concept. It may have some other purpose buried in the prior art and even if this is not discernible, the patentee may have had some reason of his own for introducing it." (h) It also follows that where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context. A good example of this is the Catnic case itself – "vertical" in context did not mean "geometrically vertical", it meant "vertical enough to do the job" (of supporting the upper horizontal plate). The so-called "
"the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge."