.

Skilled witnesses may hear the evidence of ordinary witnesses in regard
to the case in which they are to give evidence, and it is, indeed,
better that they should understand the case thoroughly, but they are not
usually allowed to hear the evidence of other expert witnesses.

In civil cases the medical witness should, previous to the trial, make
an agreement with the solicitor who has called him with reference to the
fee he is to receive. Before consenting to appear as a witness the
practitioner should insist on having all the facts of the case put
before him in writing. In this way only can he decide as to whether in
his opinion the plaintiff or defendant is right as regards the medical
evidence. If summoned by the side on which he thinks the medical
testimony is correct, then it is his duty to consent to appear. If,
however, he is of opinion that the medical evidence is clearly and
correctly on the opposite side, then he ought to refuse to appear and
give evidence; and, indeed, the lawyer would not desire his presence in
the witness-box unless he could uphold the case.

Whether an expert witness who has no personal knowledge of the facts is
bound to attend on a subpoena is a moot point. It would be safer for him
to do so, and to explain to the judge before taking the oath that his
memory has not been sufficiently 'refreshed.' The solicitor, if he
desires his evidence, will probably see that the fee is forthcoming.

A witness may be subjected to _three_ examinations: first, by the party
on whose side he is engaged, which is called the 'examination in chief,'
and in which he affords the basis for the next examination or
'cross-examination' by the opposite side. The third is the
're-examination' by his own side. In the first he merely gives a clear
statement of facts or of his opinions. In the next his testimony is
subjected to rigid examination in order to weaken his previous
statements. In the third he is allowed to clear up any discrepancies in
the cross-examination, but he must not introduce any new matter which
would render him liable to another cross-examination.

The medical witness should answer questions put to him as clearly and as
concisely as possible. He should make his statements in plain and simple
language, avoiding as much as possible technical terms and figurative
expressions, and should not quote authorities in support of his
opinions.

An expert witness when giving evidence may refer to notes