THE ENGINEEK AS WITNESS 39 



question. So where the question was whether a bank which had 

 been erected to prevent the overflowing of the sea had caused 

 the choking up of a harbour, the opinions of scientific men as 

 to the effect of such an embankment upon the harbour was 

 held to be admissible (Folkes v. Chadd, 1782, 3 Doug. 157). 



Accordingly, the opinion of an engineer would be admissible 

 in relation to works or structures which he had never seen ; 

 although of course the fact that he had seen and inspected for 

 himself would increase the value of his testimony. 



3. The duties of an expert witness Generally. Engineers 

 are often called both as witnesses upon facts and matters of 

 scientific opinion. Thus in the case of a dispute between an 

 employer and a contractor as to the quality of the works 

 which have been executed, it will be the duty of the engineer, 

 who has probably had the supervision of the work throughout, 

 to state in detail in what way the contractor has failed to 

 comply with the specifications. But the engineer is sometimes 

 called to criticise work which he has not seen in the course of 

 erection ; and his testimony will then be largely of an expert 

 character. He will be asked to assume certain facts and give 

 his opinion upon the facts assumed. 



When he is consulted as an expert pure and simple, his first 

 introduction to the dispute takes place in the following way. 

 He is approached by a firm of solicitors whose clients desire 

 him to give evidence on their behalf. Plans, drawings, and 

 a copy of the correspondence between the parties will be 

 submitted to him ; and he may also be asked to view the works 

 which form the subject-matter of the dispute. Until he has 

 read all the documents and considered the whole position from 

 the point of view of an expert, he should, it is submitted, 

 refrain from giving any undertaking to appear as a witness ; 

 for it may be that, knowing the facts, he will be unable to 

 support the case which those who instruct him are anxious to 

 put forward. In this particular his position is wholly different 

 from that of the solicitor or advocate acting on behalf of a 

 client. A lawyer may advise his client that he has no case, 

 but it may still be his duty to fight it to the best of his ability ; 

 but the expert who rushes blindly in to the support of a case 

 into which he has not inquired runs grave risk of doing more 

 harm than good. His evidence in chief may be plausible 

 enough; his proof may contain nothing which he does not 



