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Supreme Court 14 September 2023

R v So (No 3)

[2023] NSWSC 1113

Homicide
EVIDENCE ADMISSIBILITY EXPERT EVIDENCE

Citation: R v So (No 3) [2023] NSWSC 1113
Court: Supreme Court of New South Wales
Date: 14 September 2023
Judge(s): Ierace J

Background

The accused was charged with murdering a man at a rural property at Elong Elong between 14 and 15 June 2016. The Crown alleged that the accused attacked the deceased at his residence following a dispute about whether she could stay with him on an ongoing basis, intending to cause at least grievous bodily harm. The trial proceeded before a judge alone at Dubbo.

A forensic examination of the deceased's bedroom in 2017, over a year after his disappearance, revealed dried blood attributed by DNA analysis to him on the underside of the bedroom carpet. The Crown sought to lead expert evidence interpreting that blood evidence, including an opinion from a forensic pathologist estimating the volume of blood that had caused the staining.

Before the trial commenced, the accused applied under section 192A of the Evidence Act 1995 (NSW) for a pre-trial ruling on the admissibility of that expert evidence. Two proposed witnesses were at issue: Senior Sergeant Scott Gane, a forensic police officer, and Dr Allan Cala, a forensic pathologist.

Legal Issues

  • Whether Senior Sergeant Gane and Dr Cala each possessed "specialised knowledge" within the meaning of section 79(1) of the Evidence Act, derived from training, study or experience, sufficient to ground their proposed opinions.
  • Whether Dr Cala's opinion as to the estimated volume of blood causing the carpet stains was wholly or substantially based on such specialised knowledge.
  • Whether the probative value of the expert evidence was outweighed by the danger of unfair prejudice under section 137 of the Evidence Act.

Decision

Issue 1: Whether an established area of specialised knowledge exists for blood volume estimation from dried stains

The court found it was common ground that no course of training or study could equip a witness to give an opinion about the quantity of blood that caused dried stains on the underside of absorbent material, particularly without a corresponding image of blood on the upper surface (at [63]). The question therefore reduced to whether the proposed experts possessed relevant specialised knowledge derived from experience.

Issue 2: Admissibility of Senior Sergeant Gane's opinion

Ierace J admitted Senior Sergeant Gane's opinion that a "significant blood shedding event" had occurred in the bedroom (at [73]). Senior Sergeant Gane did not attempt to quantify the blood volume in precise terms; rather, he combined his observation of dried blood spatter on the bedroom walls with the staining found under the carpet and on the mattress beading to reach that broader conclusion (at [64]). His qualifications and experience as a crime scene investigator, including his certificate in crime scene methodology and completion of bloodstain pattern analysis training, were unchallenged (at [14]).

Issue 3: Admissibility of Dr Cala's blood volume estimate

The court excluded Dr Cala's opinion that the blood loss "could be well in excess of one litre" and was "possibly of the order of several litres" (at [65], [69]). Dr Cala identified three bases for his expertise: viewing crime scenes, conducting a 1994 experiment in which pathologists estimated blood quantities poured onto a tiled floor, and certain training courses, the most recent of which was in 2000 (at [25], [32]). The court found, on the balance of probabilities, that these did not establish specialised knowledge adequate to ground the opinion (at [69]).

Ierace J accepted the evidence of the accused's experts, Dr Mark Reynolds and Professor Johan Duflou, that published studies consistently demonstrate that medical professionals cannot accurately estimate blood volumes, and that familiarity with blood through forensic pathology work does not itself confer that capacity (at [66], [69]). The court also found that Dr Cala had not explained the pathway by which his experience informed his specific estimates, as required by the principles in Dasreef Pty Ltd v Hawchar and Makita (Australia) Pty Ltd v Sprowles (at [70]). Additionally, conducting the 1994 experiment did not logically enhance Dr Cala's own accuracy, as he designed it rather than participated in it as an estimator (at [68]).

Issue 4: Partial admissibility of Dr Cala's other opinions, and the physical evidence

The court held that Dr Cala's opinions about the medical consequences of blood loss and about blood spatter fell within his specialised knowledge as a forensic pathologist and were admissible under section 79(1) (at [72]). The stained carpet itself, including photographs and the results of forensic procedures conducted on it, was also admitted as relevant to facts in issue (at [74]).

Orders Made

  • Dr Cala's proposed evidence concerning the volume of blood that produced stains on the carpet in the bedroom is inadmissible.
  • Dr Cala's proposed evidence concerning the volume of blood loss that may be fatal in the absence of medical care is admissible.
  • Senior Sergeant Gane's proposed evidence that a significant blood shedding event occurred in the bedroom, and his reasoning for that opinion, is admissible.
  • The stained carpet, images of that carpet, and the results of forensic procedures conducted on it are admissible.

Key Takeaways

  • Under section 79(1) of the Evidence Act 1995 (NSW), an expert's opinion must be wholly or substantially based on specialised knowledge derived from training, study or experience; an expert must also explain the pathway by which that experience informed the specific opinion expressed, as confirmed by reference to Dasreef Pty Ltd v Hawchar and Makita (Australia) Pty Ltd v Sprowles (at [61], [70]).

  • Familiarity with blood as a routine aspect of forensic pathology practice does not, without more, constitute specialised knowledge capable of grounding an opinion about the volume of blood that caused dried stains on absorbent material, particularly where published research demonstrates that medical professionals generally cannot perform such estimates accurately (at [69]).

  • A broader qualitative conclusion, such as that a "significant blood shedding event" occurred, may be admissible where it is grounded in the combination of multiple forensic observations and supported by established crime scene investigation expertise, even where a precise quantitative estimate is not (at [64], [73]).

  • The Supreme Court distinguished the earlier decision in R v Ruttley (No 2) [2017] NSWSC 878, noting that published studies on the inaccuracy of blood volume estimation by medical professionals were not before the court in that case, and that one relevant paper had not yet been published at the time (at [76]).

  • Where an expert has conducted an experiment demonstrating that others cannot accurately estimate blood volume, that does not logically enhance the expert's own ability to make such estimates, particularly where the expert designed rather than participated in the exercise (at [68]).

Legislation and Cases Referenced

Legislation
- Evidence Act 1995 (NSW), ss 76, 79(1), 137, 192A

Cases
- Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588; [2011] HCA 21
- Makita (Australia) Pty Ltd v Sprowles (2001) 52 NSWLR 705; [2001] NSWCA 305
- R v Niguidula (No 2) [2023] NSWSC 476
- R v Ruttley (No 2) [2017] NSWSC 878