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Supreme Court 8 March 2016

R v Gordon (No 5)

[2016] NSWSC 315

Homicide
CRIMINAL LAW EVIDENCE EXPERT EVIDENCE

Citation: R v Gordon (No 5) [2016] NSWSC 315
Court: Supreme Court of New South Wales
Date: 8 March 2016
Judge: Campbell J

Background

The accused stood trial for murder. A central issue in the case was how trace DNA from both the accused and the deceased came to be found on a large 21-kilogram rock, which the Crown alleged was the murder weapon.

A Crime Scene Officer, Senior Constable Vercoe, was giving evidence about the procedures she followed when collecting and preserving evidence at the crime scene on 7 November 2013. Those procedures included the frequent changing of gloves and, between major stages of evidence collection, changing her entire protective outfit.

The Crown Prosecutor asked the officer whether she knew why those procedures were adopted. Defence counsel objected, raising a challenge both to the officer's expertise and to the admissibility of the evidence under s 137 of the Evidence Act 1995 (NSW).

  • Whether Senior Constable Vercoe possessed sufficient specialised knowledge under s 79 of the Evidence Act 1995 (NSW) to give opinion evidence about the reasons for crime scene contamination procedures.
  • Whether any such opinion evidence should be excluded under s 137 of the Evidence Act 1995 (NSW) on the basis that its probative value was outweighed by the danger of unfair prejudice to the accused.

Decision

Campbell J accepted that Senior Constable Vercoe held a degree of specialised knowledge for the purposes of s 79 of the Evidence Act. She had completed a two-week training course when she began as a Crime Scene Officer, received ongoing training, and regularly read updates to police crime scene procedures. The judge noted that a university qualification is not required for a witness to qualify as an expert under s 79, which requires only specialised knowledge based on training, study, or experience.

However, the critical question was the nature and extent of that specialised knowledge. When asked in cross-examination whether she had received any training in the secondary transfer of trace DNA specifically, the officer said she did not recall. Campbell J inferred that, given her evident carefulness, she would have remembered training of that technical nature if it had been given.

The court drew a clear distinction between what the officer could and could not properly address. She could give evidence that, from her training and experience, she understood that the procedures existed to avoid cross-contamination of exhibits. She could not, however, give evidence directed specifically at the scientific question of secondary DNA transfer, as that topic lay beyond her expertise and any opinion expressed on it could not be said to be substantially based on specialised knowledge.

On the s 137 question, the court found that the jury might overestimate the significance of the officer's evidence in circumstances where the real issue at trial was whether the Crown had excluded, as a reasonable possibility, secondary transfer of trace DNA. Given the officer's relatively limited expertise on that precise scientific question, the probative value of her evidence on that topic was outweighed by the danger of unfair prejudice to the accused. The question was rejected.

Orders Made

• Question rejected - witness not permitted to give evidence directly related to secondary transfer of trace DNA
• Non publication order lifted (06 March 2017)

Key Takeaways

  • Under s 79 of the Evidence Act 1995 (NSW), specialised knowledge may arise from training, study, or experience alone, and no formal academic qualification is required for a witness to give admissible opinion evidence.
  • A distinction exists between the scope of a witness's general expertise and the specific scientific question in issue at trial. A Crime Scene Officer's practical knowledge of contamination procedures did not extend to the scientific principles of secondary DNA transfer.
  • Where a witness's expertise does not reach the precise scientific question the opinion is intended to address, any opinion on that question cannot be said to be "substantially based" on specialised knowledge, and it will not satisfy the requirements of s 79.
  • Under s 137 of the Evidence Act 1995 (NSW) in criminal proceedings, the risk of unfair prejudice includes the risk that a jury might overstate the importance or authority of evidence due to misunderstanding of its scientific limits, particularly where the witness's expertise is relatively low-level in relation to the specific issue.
  • The Supreme Court confirmed that s 137 operates as a mandatory exclusion, not a discretion: where probative value is outweighed by the danger of unfair prejudice in a criminal proceeding, the court is required by law to refuse to admit the evidence.

Legislation and Cases Referenced

Legislation:
- Evidence Act 1995 (NSW), s 79 (opinion evidence based on specialised knowledge)
- Evidence Act 1995 (NSW), s 137 (exclusion of prejudicial evidence in criminal proceedings)

Cases cited: None cited in the judgment.