Generally, where a court is faced with the problem of determining a suit before it,
such can only be solved after making an enquiry into the relevant facts of the evidence
put before it by the parties, drawing inferences from those facts, and listening to
arguments of parties to the case or of their counsel. Evidence is there from called as a
means by which those facts can be proved.
Evidence of what the witness thinks, believes or infers in regard to facts in dispute,
as distinguished from personal knowledge of the facts themselves. The Rule of Evidence
ordinarily do not permit witnesses to testify as to opinions or conclusions when this type
of evidence is expressed by an expert witness, it may be used only if scientific, technical,
or specialized knowledge will aid the trial of fact in understanding the Evidence or
determining a fact in issue.
Opinion Evidence refers to Evidence of which the witness thinks, believes, or infers
in regard to facts as distinguished from personal knowledge of the facts themselves. In
common law jurisdictions, the general rule is that a witness is supposed to testify as to
what was observed and not to give an opinion on what was observed. However, there are
two exceptions to this rule: Expert Evidence and Non-expert Evidence opinion given by
laymen which people in their daily lives reach without conscious rationalization.