The rule in [name withheld] v [name withheld] does not require a cross-examiner to put alternative facts to an expert witness where the challenge is to the factual foundations of the expert's opinion rather than to the expert's own credit; it is for the party calling the expert to re-examine on alternative factual bases if they wish to maintain the opinion. A jury is not bound to accept uncontradicted expert opinion evidence and may reject it where the factual premises are defective or unidentified. Expert opinion evidence based on the accused's evidence generally, without identification of specific factual premises, is inadmissible or of little value.
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