Rules of Evidence
Opinion - Exceptions
Regulatory Certificates and Documents
Sub-section 2 of section 76 allows an exception where an Act or regulations provide that a document or certificate made under them has evidentiary effect, such document or certificate is admissible in evidence in spite of it being in the way of opinion.
A person may make an assessment of someone’s age, their sobriety or the speed they are driving at, for example. These assessments are based on what the witness themselves has seen, heard or otherwise perceived. This requirement means that mere speculation is not allowed. Such opinions are largely, if not entirely subjective, and are most certainly less accurate than an objective measure. Nevertheless courts allow this sort of evidence under section 78. A lay opinion will only be allowed if it is needed to acquire a complete picture of the witness’s understanding of the facts.
Aboriginal and Torres Strait Islander Traditional laws and Customs
A view expressed by a Aboriginal or Torres Strait Islander group about the existence or non-existence, or content of, any traditional laws or customs of their own group is exempt from the opinion rule.
Opinions based on specialised knowledge are exempt form the opinion rule subject to section 79. Where a witness has specialised knowledge and acquired that knowledge through training study or experience and the opinion given is based entirely or mostly on that knowledge, then the opinion qualifies for the exemption.
Specialised knowledge is defined very broadly, so it does not have to be that of a profession or a commonly recognised area of study. The definition in sub-section 1 should only serve to exclude subjective belief, and the opinions of people who have drawn conclusions with less than ideal learning, or who cannot establish that they are highly experienced or well read on the given topic. Examples of inexpert opinions that would be inadmissible include police and interpreters who identify the identity of a voice in a telephone intercept based on repeated comparisons with undisputed recordings.
In sub-section 2 it is specified, merely to avoid doubt, that such knowledge includes that of child development and behaviour, and the impact of child sexual abuse.
Abolition of Ultimate Issue and Common Knowledge rules
It was the rule that where a witness expresses an opinion about an issue to be decided on by the court, or where a witness gives an opinion about a matter of common knowledge, then such evidence is inadmissible. These common law rules have been abolished by the Uniform Evidence Law, section 80 so that such opinions can be considered by the court. This does not affect the inadmissibility of other kinds of opinions.
 Beale, Christopher W, QC, Pocket Evidence Law, Foley’s List, Melbourne, 2014, p12, citing R v Leung & Wong  47 NSWLR 405; Li v The Queen  139 A Crim R 281.
 Northern Territory Government, Department of Justice, Discussion Draft of the Uniform Evidence Act for the Northern Territory, Darwin, 2011, p 50.
All statutory sections from unspecified Acts, are sections from a model Act of the Commonwealth Parliament as described on the first page of this chapter, and should be replicated as described in each of the related Acts of each State and Territory. (Jurisdiction to regulate the rules of evidence exists in the States and Territories and not in the Commonwealth).