Citation: R v Tatola (No. 2) [2023] NSWDC 387
Court: District Court of New South Wales
Date: 11 September 2023
Judge(s): Montgomery DCJ
Background
The accused faced a charge of penile-vaginal sexual intercourse without consent. Following the alleged offence, a Sexual Assault Investigation Kit (SAIK) examination was conducted on the complainant. That examination found no semen or spermatozoa anywhere in the vaginal corridor or on the external labia.
However, an endocervical swab (taken from the highest point of the vaginal canal) returned a positive screening result for male DNA, derived not from spermatozoa but from what was described in submissions as a blood source, though the Crown noted it could originate from other sources. The male DNA matched a Y-STR profile consistent with the accused, a profile expected to occur in approximately one in 750 unrelated males in the general population.
The parties had also agreed to a fact that the accused digitally penetrated the complainant. That admitted conduct was not the subject of the charge. The central contested fact at trial was whether penile-vaginal penetration occurred. The admissibility of the blood-source DNA evidence was the subject of this ruling.
Legal Issues
- Whether the probative value of the endocervical swab DNA evidence (derived from a non-spermatozoa, likely blood source) was outweighed by the danger of unfair prejudice to the accused under s 137 of the Evidence Act 1995 (NSW)
- Whether the risk of jury speculation about an apparent evidentiary gap justified admission of the contested DNA evidence
Decision
Issue 1: Probative value of the blood-source DNA evidence
The Crown conceded that the contested DNA finding was not determinative of whether penile-vaginal penetration had occurred, which was the central fact in issue (at [4]). Montgomery DCJ accepted that the evidence had, at best, near-zero to minimal probative value on that question (at [9]). While evidence of a standard police investigation would ordinarily be relevant, the particular finding here contributed nothing meaningful to resolving the charged offence (at [9]).
Issue 2: Risk of jury speculation justifying admission
The Crown argued that excluding the evidence would leave the jury to speculate about why no further testing had been done, and that admission would confirm a thorough investigation had been undertaken (at [5]). His Honour rejected the proposition that this concern was sufficient to tip the balance toward admission. In his view, the jury would already be informed by agreed facts that testing for spermatozoa had been carried out and returned no results, and would not be "likely" to expect or speculate about an additional blood DNA test (at [8]-[9]).
Issue 3: Danger of unfair prejudice under s 137
Montgomery DCJ held that admitting the evidence carried two distinct risks of unfair prejudice. First, the jury might speculate about its significance precisely because it appeared to relate to nothing directly relevant to the offence (at [10]). Second, the judge accepted the defence's submission about the "CSI effect," being the tendency of juries to place disproportionate weight on scientific evidence regardless of its actual relevance (at [10]). Those prejudice risks outweighed the minimal probative value, and the evidence was excluded under s 137.
Orders Made
- The blood-source endocervical swab DNA evidence is not admitted, the danger of unfair prejudice to the accused outweighing its probative value pursuant to s 137 of the Evidence Act 1995 (NSW).
Key Takeaways
- Under s 137 of the Evidence Act 1995 (NSW), evidence with near-minimal probative value on the central fact in issue may still be excluded where its admission risks causing a jury to speculate about its relevance or to place disproportionate weight on it (at [9]-[10]).
- The District Court accepted the "CSI effect" as a cognisable form of unfair prejudice: the tendency of scientific evidence to carry undue weight with a jury can itself satisfy the prejudice limb of the s 137 test, even where the Crown concedes the evidence does not resolve the key contested issue (at [10]).
- A Crown concession that contested evidence is not determinative of the central fact in issue is a significant factor in any s 137 balancing exercise; here it substantially weakened the probative value side of the ledger (at [4], [6]).
- The Crown's concern about jury speculation over evidentiary gaps does not automatically favour admission; where agreed facts adequately address the gap, that concern carries reduced weight (at [8]-[9]).
- DNA evidence matching an accused's profile is not automatically admissible: the source of the biological material and its connection to the specific act charged are critical considerations in assessing probative value (at [7], [9]).
Legislation and Cases Referenced
Legislation
- Evidence Act 1995 (NSW) , s 137
Cases
- Not stated