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In the Ikarian Reefer38 case Crosswell, J., summarised the duties and responsibilities of the expert witness as follows;
1. Expert evidence prevented to the court should be, and should be seen to be, the independent product of the expert uninfluenced as to form of content by the exigencies of litigation.39
2. An expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise. 40 An expert witness cannot assume the role of an advocate. 3. An expert witness should state the facts or assumptions on which his opinion is based. He should not omit to consider material facts which could detract from his concluded opinion. 4. An expert witness should make it clear when a particular question falls outside his expertise. 5. If an expert’s opinion is not properly researched because he considers that insufficient data is available, then this must be states with an indication that the opinion is no more than a provisional one. 6. If, after exchange of reports, an expert witness changes his view on a material matter having read the other sides’ expert’s report or for any other reason then such a change of view must be communicated to the other side and the court without any delay. Summarizing the present law of expert evidence on patents CANS According to the present law the expert can give evidence on;
The state of the art
Meaning of technical terms
Whether the product protected or sought to be protected corresponds to the scope of protection set forth in the claims
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What is the working result of a product or process.
(1993) FSR 563 at 565. Per Lord Wilberforce in Whitehouse v. Jordan, (1981) 1 WLR 246 at 256. 40 Polivitte v. Commercial Union Assurance, (1987) 1 Lloyds’ Rep. 379 c.f. Narayanan, p.473. 39