Expert and Opinion Evidence

There has been so much of confusion and conflict in expert testimony; so much discussion and difference of opinion as to the true province of the medical expert, especially in homicidal cases, and the subject has become so involved in the minds of medico-legal jurists.

Here are some of the clear statements represented with reference of great books according to the law of America.

Who is an Expert?

An expert is one who has made the subject upon which he gives his opinion a matter of particular study, practice, or observation, and he must have a particular and special knowledge upon the subject concerning which he testifies

Expert Evidence

Expert evidence is that testimony given by one, expert and specially skilled, in the subject to which it relates, or is applicable; concerning information beyond the range of ordinary observation.

The general rule of law is

The witness must only state facts and not draw conclusions or inferences from facts

It has been held that to allow witnesses to draw conclusions from facts or inferences is to usurp the province of the court or jury, and is illegal

Exceptions to the General Rule

While these are the general rules of law, there are exceptions where the opinions of skilled experts may be taken as before stated

• In cases of necessity, where it is impossible to make the court and jury understand the matter in controversy without it.
• To inform the court or jury as to physical laws or phenomena, which practice dates back to the old Roman law
• To show the results of voluminous facts collated by acompetent person who has examined and is shown to becompetent to make the deductions

Opinion and Opinion Evidence

Opinion evidence is the conclusions or opinions of witnesses concerning propositions based upon ascertained or supposed facts, by one who has had superior opportunities and greater knowledge than the ordinary person or witness, to judge of the subject-matter of the inquiry, and who, by reason of his especial knowledge of, and experience with the subject, is believed to be capable of arriving at a better and more reliable conclusion and judgment, from facts within his own knowledge, concerning the questions involved in the inquiry or controversy.

• Any witness not an expert, who personally knows the facts, may give an opinion in a matter regarding skill, after having stated the facts on which he bases his opinion; or asto matters with which he is especially acquainted, or has personal or peculiar knowledge, but which cannot be exactly or specifically described to the court or jury.
• An expert physician may testify concerning the health of a certain person whom he knows personally, or has treated, and so may any witness not an expert, as to facts within his knowledge and observation, regarding the health or physical condition of another, or whether he was or had been apparently in good health.
• A physician or surgeon, shown to be competent, may give his opinion as to the probable effect of wounds and injuries, after he has viewed the body and examined the wounds, and as to whether the wounds or injuries would produce death.
• A non-expert cannot testify as to the effect of wounds or injuries.
• Physicians shown to be qualified may testify and give opinions.