24. DNA Evidence — Admissibility & Lawfulness (Vic)¶
Scope and currency
Cheat sheet (technical) · Evidence Act 2008 (Vic) ss 55–137 · Crimes Act 1958 (Vic) ss 464–464ZL · Crimes Act 1914 (Cth) Pt 1D · current to 6 July 2026
Two independent attacks on DNA — run both.
(A) Admissibility of the opinion — the Evidence Act chain: relevance (ss 55–57) → opinion rule / s 79 → s 137.
(B) Lawfulness of the sample — the forensic-procedure regime (ss 464–464ZL Vic / Pt 1D Cth) → s 464ZE / s 138. Work the gates in order; a DNA case can fall at any one of them.
A · Admissibility of the DNA opinion — the Evidence Act chain¶
GATE 1 Relevance (ss 55–57)
Could the DNA rationally affect — directly or indirectly — the assessment of a fact in issue? (s 55) s 56: relevant evidence is admissible, irrelevant evidence is not. The bar is low — but DNA fails it where the inference from the profile to the offence is speculative. The Problem of "Innocent" and "Secondary" Transfer The issue of speculative inference most frequently arises in cases involving "low-template" DNA, mixed profiles, or situations where the accused had innocent prior contact with the victim, the crime scene, or an intermediary object. Forensic science recognises that DNA can be deposited via: Primary Transfer: Direct contact (e.g., a handshake or touching a weapon). Secondary Transfer: Trace DNA is transferred by an intermediary (e.g., Person A shakes Person B's hand, and Person B then touches a weapon, depositing Person A's DNA on it). If the evidence cannot distinguish between a guilty primary transfer (e.g., stabbing the victim) and an innocent secondary transfer (e.g., touching an object that later touched the victim), the jury is left to speculate. Key Authorities on Speculative DNA Inferences The courts have consistently held that where a DNA match cannot exclude innocent transfer without speculation, the evidence has little to no probative value: Fitzgerald v The Queen (2014) 311 ALR 158: The High Court quashed a murder conviction relying on the accused's DNA found on a didgeridoo at the crime scene. The Court held that a secondary transfer of the DNA was possible, and the recovery of the DNA raised no logical inference about the time when or circumstances in which it was deposited. Because alternative hypotheses consistent with innocence could not be safely excluded, a guilty inference was not reasonably open. DPP v Wise: Secondary Transfer Case: The prosecution sought to adduce evidence of the accused's DNA found in a mixture inside the complainant's underpants to prove penile-oral penetration. However, the mixture also contained the DNA of the complainant's girlfriend, with whom no relevant sexual activity had occurred. The Court of Appeal observed that the girlfriend's DNA must have been deposited by innocent secondary transfer (such as handling drinks at the BBQ they all attended). Given this, the Court held that attempting to draw an inference that the accused's DNA was deposited via sexual assault, rather than the same innocent secondary transfer, would be "wholly speculative". DPP v Paulino: Secondary Transfer Case: The trial judge correctly excluded DNA evidence placing the accused at a murder scene because the accused and the deceased had previously lived together in that matrimonial home. The jury would have had "no reasonable basis for determining whether DNA of the accused... was connected with the killing" because innocent explanations (prior contact with the house, cars, and children) could not be rejected "without speculation". R v Joyce (2002) 173 FLR 322: Secondary Transfer Case: DNA on a complainant's clothing was excluded by the trial judge because it was common ground that the DNA could have been transferred innocently from carpets or furniture in the accused's home. The results were open to competing hypotheses, neither of which could be preferred "on any scientific basis in evidence". Forensic Application: The "CSI Effect" and s 137 As a specialist advocate, you must aggressively identify when the prosecution's DNA case requires a speculative leap. When the inference is speculative, the probative value of the DNA is inherently low. Simultaneously, the danger of unfair prejudice is extraordinarily high because of the "CSI effect"—the well-documented risk that a jury will be beguiled by the scientific pedigree of DNA testing and give it a "mantle of legitimacy" it does not deserve. In such cases, you must apply under section 137 of the Evidence Act 2008 (Vic) to exclude the evidence entirely, arguing that the very low probative value of the speculative inference is substantially outweighed by the danger that the jury will misuse the DNA as definitive proof of guilt → Relevant: on to Gate 2 (opinion rule). → Irrelevant: excluded under s 56(2) — no discretion, no need to reach s 137. DPP v Paulino [2017] VSCA 28: DNA on four items in a circumstantial murder; each item must be relevant on its own before it is "wound into a piece of string made up of multiple strands of circumstantial evidence"; ruled irrelevant / low PV / high prejudice, upheld on appeal.
GATE 2 Opinion rule & the s 79 exception (ss 76–80)
DNA interpretation is opinion evidence, so s 76 excludes it unless an exception applies. The gateway is s 79(1) Expert Opinion. s 79(1): a person with specialised knowledge based on training, study or experience may give an opinion wholly or substantially based on that knowledge. Three admissibility requirements — all go to admissibility, not weight: (i) an identified field of specialised knowledge; (ii) the opinion is wholly or substantially based on it — Dasreef Pty Ltd v Hawchar [2011] HCA 21 (failure to demonstrate the connection goes to admissibility); (iii) the reasoning is exposed — the expert must explain how the specialised knowledge applies to the facts (Makita (Australia) Pty Ltd v Sprowles). → Basis rule: Dasreef — s 79 does not import the common-law "basis rule" as a strict rule of admissibility, but if the factual foundation is not laid the opinion lacks a rational relationship to the facts and is inadmissible.
GATE 2A Reliability is NOT a s 79 question — the trap
Tempted to argue the method (STRmix / likelihood ratio) is "unreliable" under s 79? Don't — you argue reliability under s 137. Honeysett v The Queen (2014) 88 ALJR 786 (approving R v Tang): "specialised knowledge" means knowledge — "more than subjective belief or unsupported speculation" — but reliability is not to be imported into the s 79 admissibility inquiry; the focus stays on the statutory words. Tuite v The Queen [2015] VSCA 148: the reliability of a DNA methodology (STRmix, probabilistic genotyping, the likelihood-ratio basis) does not determine threshold admissibility under s 79 — it is assessed under s 137. The touchstone is proof of appropriate validation; once the method is validated, challenges go to weight, not admissibility.
GATE 3 s 137 exclusion — probative value vs unfair prejudice
Is the probative value of the DNA outweighed by the danger of unfair prejudice to the accused? (s 137 — mandatory for prosecution evidence) Probative value is taken "at its highest" — IMM v The Queen [2016] HCA 14: the judge assumes the jury accepts the evidence and does not weigh its credibility or reliability (those are for the jury), except in the "limiting case" where evidence is so inherently incredible, fanciful or preposterous that no rational jury could accept it. Consequence: attack reliability on the prejudice side and on weight — not by discounting PV. Unfair prejudice — Tuite: an unvalidated method, or one presented so the jury over-weights it, is where reliability bites; the danger is the jury giving the DNA "undue weight". Statistical framing and the CSI effect live here. → Where PV is genuinely low: the secondary-transfer / speculative-inference cases below — DNA excluded under s 137 even though "taken at its highest".
s 137 traps — statistics & the prosecutor's fallacy¶
| Trap | Rule | Authority |
|---|---|---|
| Exclusion % vs frequency ratio | "1 in 100" and "99%" carry the same information; expressing a statistic as an exclusion percentage rather than a frequency ratio does not automatically make it unfairly prejudicial, provided it is accurate and comprehensible to the jury. | Aytugrul v The Queen (2012) 247 CLR 170 (on appeal from the NSW CCA) |
| Prosecutor's fallacy | Do not equate the frequency of the profile in the population (random-match probability) with the probability of guilt. "1 in a million" ≠ "a million-to-one the accused is guilty" — in a large population others share the profile. Direct the jury when the evidence is led and again in the charge. | R v Doheny & Adams 1 Cr App R 369; R v Karger (2002) 83 SASR 135; R v GK (2001) 53 NSWLR 317 |
s 137 traps — transfer, mixed profiles & the CSI effect¶
| Issue | Point | Authority |
|---|---|---|
| Secondary / transfer DNA | DNA is deposited by innocent secondary transfer (handshake, shared object, prior contact). Presence of material ≠ presence of the person: using the profile to infer the accused was present and offended can be "wholly speculative", gutting PV. | Fitzgerald v The Queen (2014) 311 ALR 158; [2014] HCA 28 — didgeridoo; secondary transfer possible on ≥2 occasions; DNA raised no inference as to when / how deposited; convictions quashed |
| Mixed / innocent-transfer profile | A mixed profile containing an innocent third party's DNA proves transference occurs; inferring that the accused's DNA in the mix bespeaks guilt is then speculative → little / no PV, excluded under s 137. | DPP v Wise [2016] VSCA 173 |
| CSI effect | The "atmosphere of scientific confidence" a jury attaches to DNA — an "unwarranted mantle of legitimacy" no direction fully cures. Where secondary transfer eviscerates PV, this prejudice substantially outweighs PV → s 137 exclusion. | DPP v Wise [2016] VSCA 173 |
| Circumstantial "string" | Each item of DNA evidence must be relevant on its own before it can join the circumstantial "string"; relevance cannot be bootstrapped from the coincidence of several items. | DPP v Paulino [2017] VSCA 28 |
Low-template DNA, mixed profiles & STRmix¶
LTDNA / probabilistic genotyping: low quality or quantity DNA produces stochastic effects — drop-in (peaks that are not true alleles) and drop-out (alleles going missing); mixed profiles with multiple or sub-optimal contributors are highly complex. STRmix is fully-continuous probabilistic genotyping (Markov Chain Monte Carlo) that models all information in the profile, including peaks below the stochastic threshold, generating weighted genotype combinations and expressly accounting for allele drop-out. It is a development within the established specialised knowledge of statistical DNA evaluation — so its reliability is a s 137 question (validation), not a s 79 threshold bar (Tuite v The Queen [2015] VSCA 148).
Section 79 is expert opinion evidence exception to the opinion rule. Low quality DNA samples using STRmix is not excludable under s 79 as fringe science, it should be run as a s 137 reliability argument wherein PV<PE.
Jury directions on DNA¶
Criminal Charge Book (no bespoke Jury Directions Act 2015 DNA warning): the judge explains the random occurrence ratio / likelihood ratio — how much more likely it is that the accused is the source than an unrelated person chosen at random — expressed mathematically ("1 in 100", "99%") or qualitatively ("extremely strong support"); warns against the prosecutor's fallacy (see above); and, where secondary transfer or innocent deposit is open on the evidence, directs the jury to weigh those alternative explanations when deciding what weight to give the DNA.
B · Lawfulness of the sample — forensic procedures (Crimes Act 1958 (Vic) ss 464–464ZL)¶
GATE 4 Is there power to take the sample?
Two-tier "reasonable grounds" gateway (s 464R): - the person is a suspect for an indictable offence; and - reasonable grounds to believe the procedure will tend to confirm or disprove their involvement. Then one of three authorities must exist: informed consent (s 464S); a Magistrates' Court order (s 464T); or senior-police authorisation of a non-intimate sample from a person 18+ (ss 464SA–464SE).
Intimate vs non-intimate (s 464(2) Vic)¶
| Type | Samples | Note |
|---|---|---|
| Intimate | blood; pubic hair; swab or washing from the external genital or anal area, buttocks, or breasts of a female (or transgender / intersex person identifying as female); dental impression | Vic: fingerprints are not a forensic procedure (separate subdivisions, e.g. s 464K) |
| Non-intimate | buccal swab / mouth scraping (saliva); hair other than pubic hair; fingernail or toenail scrapings; swab or washing from any other external body part | Senior-officer authorisation is available for non-intimate only |
| Cth (s 23WA) | mirrors Vic, but intimate also includes a photo / video of an intimate part; non-intimate also includes fingerprints, footprints, and a photo / video of a non-intimate part | Pt 1D Crimes Act 1914 (Cth) |
Which authority? (adults)¶
| Route | Trigger / test | Provision |
|---|---|---|
| Informed consent | police explain: purpose, procedure, right to a doctor/nurse, the offence suspected, evidentiary use + placement on the DNA database, the right to refuse and the consequences of refusal; the giving of the information is recorded (s 464S(2)). Consent is valid even where access to a lawyer was refused (R v Su (2003) 7 VR 13). | ss 464S, 464SC |
| Magistrates' Court order | "relevant suspect"; Mag satisfied on the balance of probabilities of reasonable grounds the person committed the indictable offence plus a listed circumstance (offender material at scene / on victim / on an object; victim material likely on the suspect; victim not found; paternity re rape, incest or a child sexual offence). Suspect must be present unless an interim order is sought (Kirsch v Dolman [2001] VSC 234). | s 464T |
| Senior-police authorisation | non-intimate sample from a person 18+ who has refused; capable of giving consent; reasonable grounds the person committed the offence; taking it without consent justified in all the circumstances. The lawyer must be given a reasonable chance to make representations; written authorisation + grounds provided to lawyer/client; s 464Y caution; reasonable force permitted. | ss 464SA–464SF |
Children & impaired persons¶
Under-18 and mental impairment: no forensic sample from a child under 12; for 12–17, only on a Children's Court order, with notice to a parent/guardian, a parent/guardian or independent person present, and the Court additionally satisfied the order is justified in all the circumstances (seriousness, degree of the child's involvement, age) — s 464U. Where a suspect cannot give informed consent because of a mental impairment, police must apply to the Magistrates' Court (s 464T of the Crimes Act 1958 (Vic).).
GATE 5 Was it done lawfully? — the admissibility consequence
Were the statutory requirements (conduct, recording, cautions, analysis, destruction) complied with? Execution: reasonable force permitted; a practitioner of the same sex where practicable; reasonable privacy; s 464Y caution (need not answer the practitioner's questions, but anything said may be given in evidence); an intimate sample other than blood/buccal is video-recorded if practicable and consented (if not consented, they VP will get an independent witness to watch). Warrant to compel attendance/detention: s 464X. → Non-compliance: s 464ZE: the results are inadmissible unless the accused consented or the court is satisfied on BOP that admission is justified. Where a sample that should have been destroyed is used, exclusion is effectively absolute. → Improperly / illegally obtained: s 138 discretionary exclusion (cross-reference to Police Powers): desirability of admitting the evidence weighed against the impropriety in obtaining it.
C · Post-conviction samples, retention & destruction¶
| Mechanism | Rule | Provision |
|---|---|---|
| Post-conviction sample | on a finding of guilt for a "forensic sample offence" (any indictable offence, or one listed in Sch 8) the court may order a sample — now routine at sentencing; application within 6 months of the final determination of any appeal / expiry of the appeal period; must specify the sample type; made in open court, else voidable (Lednar v Magistrates' Court (2000) 117 A Crim R 396); notice required for a child. | s 464ZF |
| Discretion on the order | an order does not follow automatically on a finding of guilt; the court weighs the seriousness of the offence and whether the order is justified (R v Skura [2003] VSC 290; R v Abebe [1999] VSC 214; Heriban & Brunner [2005] VSC 76; R v Lagona [1998] VSC 220). The accused has a natural-justice right to make submissions (Pavic v Magistrates' Court (2003) 140 A Crim R 113). |
s 464ZF(8) |
| Retention of a sample | sample lawfully taken; person found guilty of that offence / a related offence / one where the sample was probative; application within 6 months. | s 464ZFB |
| Appeal against the order | an order is not part of the sentence and cannot be appealed as a sentence — the only remedy is judicial review (R v Sari [2008] VSCA 137; O 56 SCR). Judicial Review: Applications for judicial review or orders in the nature of certiorari must be brought in the Supreme Court of Victoria under Order 56 of the Supreme Court (General Civil Procedure) Rules 2015. Despite arising out of a criminal matter, such proceedings for judicial review are properly characterised as criminal proceedings due to the nature of the underlying matter The Section 272 CPA Alternative (Magistrates' Court Orders): A critical forensic consideration arises if the section 464ZF order was made by a magistrate. If the order was made in the Magistrates' Court, it is a final order. Under section 272 of the CPA, a party may appeal to the Trial Division of the Supreme Court on a question of law from a final order of the Magistrates' Court. |
— |
| Registrable offender | police may direct a registrable offender to undergo a procedure where the Chief Commissioner holds no sample; personal service; 28 days to comply; sample retained indefinitely (unless the underlying finding of guilt is later overturned on appeal). | s 464ZFAB |
| Destruction | identifying information must be destroyed if the person is not charged within 12 months or is charged and then not convicted (except a mental-impairment finding), once appeal periods expire; police may apply to retain before that deadline; using material that should have been destroyed is an offence. | s 464ZG |
Commonwealth (Pt 1D Crimes Act 1914)¶
Cth offences: same architecture — informed consent, senior-officer authorisation of a non-intimate procedure, or a magistrate's order. DNA may be kept for statistical purposes, but the sample must be destroyed within 12 months of being taken if no proceeding is instituted or the proceeding is discontinued (s 23YO); time limits and special requirements apply to Aboriginal and Torres Strait Islander suspects.
Currency watch¶
• Admissibility chain — verified 6 July 2026: ss 55–137, Dasreef, Makita, Honeysett, R v Tang, Tuite, IMM, Aytugrul, Doheny & Adams / Karger / GK, Wise, Paulino, Fitzgerald, LTDNA / STRmix, and the Criminal Charge Book DNA directions.
• Evidence Act provisions are stable — ss 55–57, 76–80 and 137 are not affected by the recent (complicity / committals / consent) reforms; the DNA chain is not a currency-sensitive topic.
• Forensic-procedure regime — from source notes ss 464R–464ZG (Vic) and Pt 1D (Cth): section numbers are carried from the notes; spot-check the current numbering, which is periodically renumbered.