Opinion and expert evidence Flashcards
What are the three distinct meanings of ‘opinion’ that occur frequently in a legal context?
- ‘In my opinion’- personal belief about a fact in question
- ‘That is a matter of opinion’- there is a reasonable doubt about a fact in question
- A witness’s opinion which consists of a summary of the inferences or conclusions that a witness draws from an observed event.
Which form of ‘opinion’ is relevant and admissible?
The third form.
What is the general rule irt to opinion evidence?
The opinion of a witness is irrelevant because it is a function of the court to draw inferences and to form its own opinion from the facts.
What is the basis of the opinion rule?
It has no probative value and cannot assist the court in proving a fact in issue.
When is a witness’s statement relevant and admissible?
When it is an objective statement of fact about a directly observed event.
What is the ultimate issues doctrine?
It is the opinion rule that protects the fact-finding function of a court and states that only a court, and not a witness, can express an opinion about an ultimate fact in issue.
What does the opinion rule hold?
The opinion evidence of laypersons and experts is irrelevant and inadmissible when it is superfluous and cannot assist the court because a court can form its own opinion or inferences about a fact in issue.
What is the exception to the opinion rule?
The opinion evidence of laypersons and experts is relevant and admsisible when the witness is in a better position to form an opinion than the court and such an opinion will assist the court in determining a fact in issue.
Which cases deal with the exception to the opinion rule?
- R v Vilbro (school inspector)
- S v Mlimo (police officer with no high education qualification)
- Holtzhauzen v Roodt (clinical psychologist rape case)
What are the two instances in which opinion evidence becomes relevant and admissible?
- The opinion of a layperson is relevant and admissible on certain issues which fall within the competence and experience of laypersons generally
- Expert opinion evidence in the form of an appropriately qualified expert or an experienced and skilled laypersons is always admissible to assist the court in determining facts in issue that require specialist knowledge not available to the court.
When is the opinion of a witness considered superfluous and inadmissible?
- Give an opinion as to the legal merits of case
- An opinion that results in a conclusion of law or that interprets the meaning of words in a statute.
What are inferences based on opinion?
An opinion based on a summary of factual data as perceived by the witness.
What happens if the witness’s opinion is an inference based on pinion?
Court will allow the witness’s observations to be conveniently communicated to the court in the form of an opinion.
When does expert opinion become relevant?
When the court cannot decide on issues without expert guidance.
Which case deals with the admissibility of expert opinion?
Gentiruco AG v Firestone.