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  • Writer's pictureGeoff Harrison

Expert Evidence

Updated: Nov 3, 2023


Best Barrister, Best Lawyer, Best Solicitor, Best Criminal Barrister, Criminal Lawyer, Criminal Barrister, Criminal Solicitor, Expert Evidence,

Published by Geoff Harrison | 8 October 2023


As a general rule a witness is not permitted to give an opinion in court as per s76 of the Evidence Act 1995 ('the Act') eg. "I think...", "I believe....". Witnesses are generally only permitted to give evidence of things that they have actually perceived eg. "I seen..." and "I heard...". Exceptions to the opinion rule include Lay Opinion, however, again it must be based upon what the witness saw, heard or otherwise perceived: s78 of the Act eg. Intoxication and estimates of speed.


The main exception to the Opinion Rule is Expert Evidence which must be specialised knowledge that is based upon the person's training, study or experience: s79 of the Act. The expert must be able to demonstrate the factual and intellectual basis for their opinion: Makita v Srowle at [85]. A Witness is bound the Expert Code of Conduct: see Schedule 7 of the Uniform Civil Procedure Rules 2005. The Expert's duty is to the court and not as an advocate for a party hence, the expert is to be impartial. A clear breach of this duty was in the case of Wood v R, where A/Prof Cross had conducted poorly designed experiments with motives that clearly crossed lines in regard to impartiality.


A party is able to tender Expert Certificates, without calling the expert, provided the requirements of s177 of the Act are complied with and it is served 21 days prior to the hearing. However, a party may by written notice (s177(5)) require the Expert for cross-examination. However, if the court is of the view that the Expert was called without reasonable cause for cross-examination, cost orders can be imposed: s177(7).


Where there is more than one Expert involved the court can make orders as to how and when the experts are to give evidence which includes the giving of evidence concurrently, colloquially known as 'hot tubbing': s275C Criminal Procedure Act 1986.


Other Sources:


Cases:


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Extracted Legislation:


EVIDENCE ACT 1995 - SECT 76

The opinion rule


(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.

Note : 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.


EVIDENCE ACT 1995 - SECT 77

Exception: evidence relevant otherwise than as opinion evidence


The opinion rule does not apply to evidence of an opinion that is admitted because it is relevant for a purpose other than proof of the existence of a fact about the existence of which the opinion was expressed.


EVIDENCE ACT 1995 - SECT 78

Exception: lay opinions


The opinion rule does not apply to evidence of an opinion expressed by a person if--


(a) the opinion is based on what the person saw, heard or otherwise perceived about a matter or event, and

(b) evidence of the opinion is necessary to obtain an adequate account or understanding of the person's perception of the matter or event.


EVIDENCE ACT 1995 - SECT 78A

Exception: Aboriginal and Torres Strait Islander traditional laws and customs


The opinion rule does not apply to evidence of an opinion expressed by a member of an Aboriginal or Torres Strait Islander group about the existence or non-existence, or the content, of the traditional laws and customs of the group.


EVIDENCE ACT 1995 - SECT 79 Exception: opinions based on specialised knowledge

Exception: opinions based on specialised knowledge


(1) If a person has specialised knowledge based on the person's training, study or experience, the opinion rule does not apply to evidence of an opinion of that person that is wholly or substantially based on that knowledge.


(2) To avoid doubt, and without limiting subsection (1):


(a) a reference in that subsection to specialised knowledge includes a reference to specialised knowledge of child development and child behaviour (including specialised knowledge of the impact of sexual abuse on children and their development and behaviour during and following the abuse); and


b) a reference in that subsection to an opinion of a person includes, if the person has specialised knowledge of the kind referred to in paragraph (a), a reference to an opinion relating to either or both of the following:


(i) the development and behaviour of children generally;


(ii) the development and behaviour of children who have been victims of sexual offences, or offences

similar to sexual offences.


EVIDENCE ACT 1995 - SECT 80

Ultimate issue and common knowledge rules abolished


Evidence of an opinion is not inadmissible only because it is about--


(a) a fact in issue or an ultimate issue, or

(b) a matter of common knowledge.


EVIDENCE ACT 1995 - SECT 177

Certificates of expert evidence


(1) Evidence of a person's opinion may be adduced by tendering a certificate (

"expert certificate" ) signed by the person that--

(a) states the person's name and address, and

(b) states that the person has specialised knowledge based on his or her training, study or experience as specified in the certificate, and

(c) sets out an opinion that the person holds and that is expressed to be wholly or substantially based on that knowledge.


(2) Subsection (1) does not apply unless the party seeking to tender the expert certificate has served on each other party--

(a) a copy of the certificate, and

(b) a written notice stating that the party proposes to tender the certificate as evidence of the opinion.


(3) Service must be effected not later than--

(a) 21 days before the hearing, or

(b) if, on application by the party before or after service, the court substitutes a different period--the beginning of that period.


(4) Service for the purposes of subsection (2) may be proved by affidavit.


(5) A party on whom the documents referred to in subsection (2) are served may, by written notice served on the party proposing to tender the expert certificate, require the party to call the person who signed the certificate to give evidence.


(6) The expert certificate is not admissible as evidence if such a requirement is made.


(7) The court may make such order with respect to costs as it considers just against a party who has, without reasonable cause, required a party to call a person to give evidence under this section.


CRIMINAL PROCEDURE ACT 1986 - SECT 275C

Court may direct expert evidence be given concurrently or consecutively


(1) The court may, at any time, give directions as it considers appropriate to enable the giving of expert evidence concurrently or consecutively in criminal proceedings.


(2) Directions under this section may include the following--

(a) a direction that an expert witness give evidence at any stage of the proceedings,

(b) a direction that more than one expert witness give evidence at the same time in the proceedings,

(c) a direction that an expert witness give an oral exposition of the witness's opinion on a particular matter,

(d) a direction that an expert witness be examined, cross-examined or re-examined in a particular manner or sequence, including by putting to each expert witness, in turn, each question relevant to one matter or issue at a time,

(e) a direction that an expert witness be permitted to ask questions of another expert witness who is giving evidence at the same time during the proceedings.


(3) A direction may be given under this section only with the consent of the prosecutor and the accused person.


(4) This section does not limit any other powers of a court to give directions in relation to evidence, witnesses or the management and conduct of proceedings.







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