LEGAL PRINCIPLE: EVIDENCE – Expert Witness – Evaluation of Conflicting Expert Testimony
PRINCIPLE STATEMENT
If in light of other relevant credible evidence the expert's evidence is not or cannot be true, it cannot be said to be uncontradicted and the court is entitled to reject it; the existence of other relevant and credible evidence showing the expert's evidence is not or cannot be true constitutes good reason for rejecting it.
RATIO DECIDENDI (SOURCE)
"If in the light of other relevant credible evidence before the court the evidence of the expert is not or cannot be true it cannot be said to be uncontradicted and the court will be entitled to reject it. Indeed, the existence of other relevant and credible evidence before the court showing that the evidence of the expert is not or cannot be true will constitute a good reason for rejecting it."
EXPLANATION / SCOPE
Expert testimony, while entitled to respect, isn’t sacrosanct. Courts aren’t bound to accept expert opinions contradicted by other credible evidence. When lay testimony, documentary evidence, or demonstrable facts conflict with expert opinions, courts may prefer the non-expert evidence if more reliable. For example: an expert opines a signature is genuine, but multiple witnesses testify they saw someone else sign; an expert estimates property value, but recent comparable sales establish different values. Courts assess: the expert’s methodology, assumptions, whether they considered all relevant facts, and consistency with other evidence. “Uncontradicted” expert evidence typically receives weight, but evidence contradicted by credible alternatives can be rejected. This prevents experts from trumping common sense or established facts and maintains judicial fact-finding authority.