Citation: R v Cairney (No 19) [2025] NSWSC 783
Court: Supreme Court of New South Wales
Date: 16 June 2025
Judge: Campbell J
Background
This decision arises in a criminal trial in which the accused, referred to here as the defendant, faces charges relating to a fatal interaction with another person at a residential property in Wollongong. A significant factual dispute emerged during the trial about where precisely within the backyard of the property the fatal incident occurred, with lay witness evidence raising competing accounts.
The Crown sought to lead expert opinion evidence from Detective Senior Sergeant Moon, a senior officer and coordinator of the Wollongong crime scene investigation section, who holds a level 3 accreditation in bloodstain pattern analysis. A more junior officer, Sergeant Cajna, who held a level 2 accreditation at the time of the investigation in December 2022, had already given evidence before the jury.
Defence counsel objected to the Senior Sergeant's evidence on the basis that he had not conducted an independent analysis, but had merely adopted the opinions of Sergeant Cajna. Campbell J heard the objection on a voir dire, the process by which a court determines the admissibility of evidence in the absence of the jury.
Legal Issues
- Whether Detective Senior Sergeant Moon formed his own independent opinion, or merely adopted the conclusions of a more junior analyst, such that his evidence would not meet the requirements for expert opinion evidence under s 79 of the Evidence Act 1995 (NSW)
- Whether the Crown could put leading questions to the Senior Sergeant during evidence-in-chief, pursuant to s 37(1)(e) of the Evidence Act
Decision
Issue 1: Independence of the expert's opinion
Campbell J rejected the submission that Sergeant Moon had done no more than adopt Sergeant Cajna's opinions. His Honour found that the process was more nuanced, describing it as akin to a technical or peer review (at [5]). The Senior Sergeant considered Sergeant Cajna's statement, a large number of crime scene photographs, the forensic pathologist's opinion, and other secondary materials identified in his statement before forming his conclusions.
The judge was satisfied that Sergeant Moon formed his own independent opinion based on that material, and that forming opinions by reference to secondary materials is a legitimate method within bloodstain pattern analysis (at [5]). Although the Senior Sergeant attended the crime scene only briefly on the night in question, his Honour found this did not undermine, devalue, or delegitimise the opinion he had formed through his technical review (at [6]).
Campbell J also noted that the Senior Sergeant had confirmed he had read the expert witness code of conduct under Schedule 7 of the Uniform Civil Procedure Rules 2005 (NSW) and agreed to be bound by it, a matter the judge described as not insignificant (at [7]).
His Honour concluded that the evidence was properly admissible as expert opinion within the Senior Sergeant's branch of specialised knowledge, subject to compliance with the conditions in s 79 of the Evidence Act (at [8]).
Issue 2: Leading questions in evidence-in-chief
Campbell J initially ruled that leading questions were permissible of an expert witness under s 37(1)(e) of the Evidence Act unless otherwise ordered (at [4]). Following the voir dire ruling on admissibility, his Honour confirmed that the Crown should be given leeway to ask leading questions of the Senior Sergeant in evidence-in-chief (at [9]).
Orders Made
- The evidence of Detective Senior Sergeant Moon is properly admissible as expert evidence within his branch of specialised knowledge, subject to compliance with s 79 of the Evidence Act 1995 (NSW)
- The Crown is to be given leeway in asking leading questions of Detective Senior Sergeant Moon in evidence-in-chief
Key Takeaways
- An expert who conducts a technical or peer review of secondary materials generated during an investigation, including photographs, statements, and other reports, can form an independent expert opinion sufficient to satisfy s 79 of the Evidence Act, provided the expert brings their own specialist judgment to bear on that material (at [5]-[6]).
- The fact that a senior analyst did not personally conduct the primary crime scene examination does not, of itself, render their opinion inadmissible or undermine its legitimacy where the opinion was formed through a structured review of relevant investigative materials (at [6]).
- A higher level of accreditation than the primary attending analyst is relevant context, but the critical question is whether the reviewing expert formed their own independent view rather than simply adopting another's conclusions (at [3], [5]).
- Confirmation by an expert witness that they have read and agreed to be bound by the expert witness code of conduct under Schedule 7 of the Uniform Civil Procedure Rules 2005 (NSW) was treated by the Supreme Court as a relevant, positive consideration in assessing admissibility (at [7]).
- Under s 37(1)(e) of the Evidence Act, leading questions are generally permissible of an expert witness in chief unless the court orders otherwise; a ruling that an expert's opinion evidence is admissible may support the Crown being given leeway to use leading questions during that evidence (at [4], [9]).
Legislation and Cases Referenced
Legislation
- Evidence Act 1995 (NSW) ss 37 , 79
- Uniform Civil Procedure Rules 2005 Sch 7
Cases
- Not stated