Expert Evidence on Obviousness

1The task of the expert is to give evidence with regard to the state of the art at a given point of time. The expert evidence with regard to obviousness will involve the personal opinion of the witness. Such evidence, regardless of whether called upon by the plaintiff or the defendant, is of limited value as they are necessarily of speculative character and often leads to conflicting views. (See Minnesota Mining and Manufacturing Co v Bondina Ltd (1973) RPC 491, p 536, [1972] FSR 331.) The expert must not give evidence with regard to what is contained in the specification in issue. The expert cannot state whether any step is obvious, as it is the duty of the court to determine obviousness. (See British Celanese Ltd v Courtaulds Ltd (1935) 52 RPC 171, p 196. See also American Cyanamid Co v Ethicon Ltd (1979) RPC 215, p 251 (Ch D).) The expert is necessary ’to ascertain what whole phrases and sentences in the specification, provided they are technical, mean when read by those instructed in the art to whom it is addressed’. (See American Cyanamid Co v Ethicon Ltd (1979) RPC 215, pp 252-53 (Ch D).) However, if the teaching or revelation from which the step to the particular patent is obvious is obscured by other documents or by a multiplicity of other teachings, the skilled addressee may be excused from recognising the relevant teaching. (See Dow Chemical Co (Mildner’s) Patent (1975) RPC 165, p 169 (CA).)

2In Cipla v F Hoffmann-La Roche (2015) the Division Bench concluded that Cipla’s expert “was not an ordinary person skilled in the art being a professor of the Chemistry and not a medicinal Chemist”, that he “based his theory of obviousness only on the basis of structural similarity”, and that “The evidence of DW-3 was a hindsight evidence” (para 168).