(1) Evidence of an opinion is not admissible to prove the existence of a fact about the existence of which the opinion was expressed.
(2) Subsection (1) does not apply to evidence of an opinion contained in a certificate or other document given or made under regulations made under an Act other than this Act to the extent to which the regulations provide that the certificate or other document has evidentiary effect.
Specific exceptions to the opinion rule are as follows:• summaries of voluminous or complex documents (section 50 (3))• evidence relevant otherwise than as opinion evidence (section 77)• lay opinion (section 78)• Aboriginal and Torres Strait Islander traditional laws and customs (section 78A)• expert opinion (section 79)• admissions (section 81)• exceptions to the rule excluding evidence of judgments and convictions (section 92 (3))• character of and expert opinion about accused persons (sections 110 and 111).Other provisions of this Act, or of other laws, may operate as further exceptions.
Examples:1 P sues D, her doctor, for the negligent performance of a surgical operation. Unless an exception to the opinion rule applies, P’s neighbour, W, who had the same operation, cannot give evidence of his opinion that D had not performed the operation as well as his own.2 P considers that electrical work that D, an electrician, has done for her is unsatisfactory. Unless an exception to the opinion rule applies, P cannot give evidence of her opinion that D does not have the necessary skills to do electrical work.