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  • The recent decisions of Dadley v R [2021] NSWCCA 267 and Franklin v R [2021] NSWCCA 260 consider the effect of unfair prejudice on the admissibility of forensic evidence.
  • In cases where DNA evidence, taken at its highest, poses unfair prejudice due to the ‘CSI effect’ and has minor probative value, it may be appropriate to rule it inadmissible pursuant to s 135 and/or s 137 of the Evidence Act 1995 (NSW).
  • However, interstate authorities and the decision of Franklin v R indicate that, other than in those cases, judges should leave forensic evidence to the jury and ameliorate potential prejudice with appropriate directions.

This article examines the recent decisions of the NSW Court of Criminal Appeal in Dadley v R [2021] NSWCCA 267 (‘Dadley) and Franklin v R [2021] NSWCCA 260 (‘Franklin’), specifically regarding the treatment of DNA evidence in view of the ‘CSI effect’. The ‘CSI effect’ refers to jurors’ willingness to attribute undeserved legitimacy to forensic evidence. This is understandable given the popularity of David Caruso and the able technicians in the CSI: Miami laboratory. Dadley and Franklin exemplify the Court’s approach to tempering jurors’ enthusiasm.

Whilst obiter in Dadley queries the admissibility of DNA evidence whose aura of legitimacy obscures its negligible probative value, Franklin indicates that, despite the ‘CSI effect’, DNA evidence with multiple interpretations should be left to the jury to form part of the totality of evidence.

Dadley v R


The appellant and complainant were colleagues who attended a Christmas party in December 2016. The complainant invited the appellant to stay at her apartment after the party, as the appellant lived far from the venue. The appellant slept in Bedroom 1 and the complainant in Bedroom 2.

The complainant gave evidence that she awoke to the appellant having sexual intercourse with her in Bedroom 2, and later the appellant moved her to Bedroom 1 where he initiated non-consensual intercourse with her a second time (Counts 1 and 2 sexual intercourse without consent per s 61L Crimes Act 1900 (NSW)). There was also an allegation of indecent assault.

It was the appellant’s contention that no sexual intercourse occurred. It was an agreed fact that the complainant ‘frog marched’ the appellant out of her apartment holding him by the hair. The complainant had a sexual assault investigation kit (‘SAIK’) performed approximately 17 to 18 hours after the alleged assault. A trace of the appellant’s DNA, which was not semen, was located inside the complainant’s vagina.

First instance

In July 2020, after a trial before Sweeney SC DCJ and a jury, the appellant was found not guilty of the first count of sexual intercourse without consent but guilty of the remainder.

Issues on appeal

There were multiple grounds of appeal raised including, relevantly, whether the verdicts of guilty were unreasonable and could not be supported having regard to the evidence.

NSWCCA decision

Bell P (Walton and Bellew JJ agreeing) held the verdicts of guilty were unreasonable. Expert evidence adduced at trial indicated an inability of the kind of DNA detected during the SAIK to survive in the vagina for more than 12 hours. It was thus was more indicative of secondary transference than any assault taking place, for example, by the complainant touching her vagina after getting the appellant’s DNA under her fingernails during the aforementioned ‘frog-march’.

Considering this, the Court cited DPP v Wise [2016] VSCA 173: ‘as a matter of pure logic, the DNA evidence has little or no probative value. By virtue of its scientific pedigree, however, a jury will likely regard it as being cloaked in an unwarranted mantle of legitimacy — no matter the directions of a trial judge — and give it weight that it simply does not deserve. The danger of unfair prejudice is thus marked, and any legitimate probative value is, at best, small’ [emphasis added] (at [70]). The Court held it was ‘impossible to escape the conclusion that the fragment of DNA which was detected in the complainant’s vagina was critical to the jury’s returning of a verdict against the Applicant’ yet had the information about the probability of secondary transference been adduced on the voir dire, its admissibility would be in doubt. This was a core component of Bell P’s ultimate decision that the convictions on Counts 2 and 3 were inconsistent with the acquittal on Count 1, and therefore the verdicts of guilty were unreasonable.

Bell P indicated that had the evidence regarding the limits of survival of the trace DNA been adduced on the voir dire, it may have been appropriate not to admit the evidence (at [128]-[130]).

Franklin v R


In April 2007 the appellant and complainant travelled to the Canberra and Goulburn region for a short vacation. On Sunday evening, when the complainant refused to have sex with the appellant, the appellant began to verbally abuse, slap and punch her.

The following morning, the appellant directed the complainant to drive, and slapped her across the face as she was driving, breaking her glasses in the process (Count 1 – common assault contrary to s 61 Crimes Act 1900 (NSW)). The complainant unsuccessfully attempted to escape the vehicle (Count 2 –
detaining a person with the intent of obtaining an advantage (sexual gratification) contrary to s 86(2)(b) Crimes Act).

After the attempted escape, the appellant punched the complainant, causing her nose to bleed. The appellant then forced the complainant to perform fellatio (Count 3 – aggravated sexual intercourse without consent contrary to s 61J(1)Crimes Act).

First instance

After a trial before Nicholson SC DCJ and a jury at the Goulburn District Court in 2009 the appellant was found guilty of all three counts.

Issues on appeal

There were multiple grounds of appeal raised including, relevantly, a ground of appeal querying the admissibility of DNA evidence adduced by the Crown at trial. This evidence was a report on blood located on the appellant’s pants. The appeal ground stated, ‘Judge Nicholson erred in admitting DAL Report 2 because it cannot provide any evidence of how or when DNA got onto the trouser and so cannot assist the prosecution in this case. Admission of the report is grossly unfair under the circumstances and likely used by the jury for impermissible speculation or unreasonable reliance on DNA’s apparent certainty in the sea of uncertainty’ (at [47]).

The significance attributed to the DNA by the Crown was that it supported a finding that the complainant’s blood was on the appellant’s pants around the fly, which tended to support her account that she had been forced to perform fellatio after being assaulted in a way that caused her nose to bleed. The expert who prepared the report gave evidence that ‘there was any number of possibilities as to the way in which… DNA came to be on the trousers.’

The appellant argued the DNA evidence ought to have been withheld from the jury as it was ‘capable of being explained by the alternative, innocent hypothesis that the DNA was placed on the pants by the appellant’ (at [62]).

NSWCCA decision

McCallum JA, Beech-Jones and Hamill JJ held the evidence was admissible. In exercising his discretion not to exclude the evidence, the trial judge was required to assess its probative value at its highest, per the rule in R v Bauer (2018) 266 CLR 56. The Court found the DNA evidence ‘was at least capable of providing support for the complainant’s evidence of the events relied upon’ (at [61]).

They observed, ‘it is not at all uncommon for DNA evidence… to be equivocal’ and mere equivocality does not render DNA evidence inadmissible. Evidence is not inadmissible solely because it is weak, and questions as to admissibility should not be conflated with questions as to whether the totality of the evidence is sufficient to sustain a jury’s verdict; this distinction was first drawn in Festa v The Queen (2001) 208 CLR 593. Evidence may be consistent with the accused committing a crime whilst also being open to alternative explanation. It is to be considered together with all other admissible evidence.


The ‘CSI effect’ is a phenomenon recognised by the ACT, Victorian and NSW Courts of Appeal, but its appropriate redress is a site of some disagreement. Dadley’s obiter, referring to DPP v Wise, indicates a preference for ruling evidence inadmissible if it is likely to attract ‘elevated significance’ which, upon close analysis, is undeserved (at [124]-[130]). However, the issue cannot always be sufficiently ventilated and disposed of at the point of voir dire, for two reasons.

Firstly, it was unclear at the voir dire stage of the Dadley trial that the evidence was flawed. Trials are the second process of enquiry that bring to light such flaws. Secondly, the more common circumstance is one where the DNA evidence undoubtedly possesses probative value but is, for technical reasons, open to multiple interpretations.

The Court in Franklin adopted the approach preferred by Festa and Bauer that practitioners and judicial officers must assist the jury to rationally interpret forensic evidence. Victorian authorities also adopt this view (Davies v R [2019] VSCA 66 at [189]; Farha v R [2018] VSCA 310 at [37]). There will always be well-founded concerns about jurors’ abilities to digest complex information. If it is suspected they will project social biases or prejudices upon the evidence, it is the role of the parties to present educational expert evidence and the role of the judge to ameliorate such biases with suitable directions. The solution is rarely to hide information from jurors for their own protection.

* The views expressed in this article are not necessarily those of the NSW Office of the DPP.

Lucy Lester is a solicitor at the NSW Office of the Director of Public Prosecutions.