Director of Public Prosecutions (NSW) v JS [2025] NSWSC 1172

Director of Public Prosecutions (NSW) v JS [2025] NSWSC 1172 · Read the judgment on AustLII

Catchwords: Evidence – Expert evidence – s 177 certificates

In this decision the Supreme Court has held that a certificate under s 177 of the Evidence Act is not required to comply with all the usual requirements for expert evidence. So long as it complies with the terms of s 177, and so long as there is no written objection, the certificate – and therefore the opinion – is admissible in the proceedings.

The defendant is a juvenile. In the Children’s Court, a Magistrate acquitted him of a charge of unauthorised possession of a pistol, contrary to s 7(1) of the Firearms Act 1996.

During a search of the defendant’s home, they took the defendant’s mobile phone. That phone had recordings of him holding what appeared to be a pistol. He was charged and duly pleaded not guilty. The prosecution, as part of its case, tendered a certificate under s 177 of the Evidence Act 1995. That certificate was given by a firearms examiner, and opined that the pistol in the videos looked like a particular (real) pistol, such that depending on the functionality of it (which couldn’t be determined from the video), it could either be a pistol, a firearm, or an imitation firearm within the meaning of the Firearms Act. No notice had been served by the defendant under s 177(5), requiring the expert to give evidence. Rather, the defendant objected to the certificate on two bases, the most relevant of which for the purposes of this summary was that the certificate didn’t reveal the ‘pathway of reasoning’ needed to demonstrate that the opinion was ‘wholly or substantially based on [the expert’s] specialised knowledge’.

The question which arose in the appeal was whether, if a certificate otherwise complies with the requirements of s 177, is it also required to comply with the requirements of s 79 of the Evidence Act, which sets out the requirements for expert evidence generally?

In this case, the Court (Payne JA, sitting alone) observed that the Magistrate’s reasoning could only be understood as requiring, as a precondition of admissibility of a certificate under s 177, separate compliance with s 79 (at [26]). The ‘opinion rule’ in s 79 of the Evidence Act (which prima facie excludes evidence of opinions) is subject to an express exception in s 79. The first condition of admissibility under s 79 is that the evidence is given by a person who has specialised knowledge based on the person’s training, study, or experience. The second condition of admissibility is that the relevant opinion is ‘wholly or substantially based’ on that ‘specialised knowledge’ (at [52]).

In relation to s 177 certificates, the better view is that the admissibility of a certificate made under s 177 is not conditioned upon both compliance with s 177 and separate satisfaction of s 79. Section 177 is intended to facilitate proof of relatively routine expert opinions (at [64]). The clear safeguard for a person served with a certificate made under s 177 is that they may, until the point the certificate is admitted in evidence, give written notice under s 177(5), at which point the certificate becomes inadmissible by reason of s 177(6). The sanction for requiring the witness to give evidence without reasonable cause is an order for costs against the party who required the witness to attend: s 177(7) (at [63]). An opinion contained in a certificate which complies with s 177 is admissible as an exception to the opinion rule unless and until the expert is required for cross-examination under s 177(5), in which case the standard of admissibility under s 79 applies (at [57]). Admission of an expert opinion under s 79(1) requires satisfaction of the two conditions set out above. But admission of an opinion contained in a certificate only requires compliance with the matters addressed in s 177 and does not require separate compliance with s 79. A key textual difference between s 177(1)(c) and s 79 is that s 177(1)(c) provides that for the certificate to be admissible, it must involve an opinion that is ‘expressed to be’ wholly or substantially based on the expert’s training, study, or experience; those words does not appear in s 79 (at [61]).

This textual analysis was supported, his Honour found, by reference to earlier appellate decisions (at [65]-[72]) and the history of the provision (at [73]-[74]). The interpretation does not give rise to any relevant unfairness because of the safeguard inherent in opposing admissibility under s 177(5). This includes that the notice may be served right up until the time when the certificate is to be admitted as evidence (at [75]). The Magistrate erred in his interpretation of s 177 and by implicitly holding that a certificate made under s 177 also had to meet the conditions of admissibility required by s 79 of the Evidence Act (at [80]). The appeal was allowed, and the matter was remitted to the Children’s Court to be dealt with according to law.

It should be observed that, although s 177 is overwhelmingly used by the prosecution, the text is explicitly agnostic about which side produces the certificate. This obviously entails a risk that the prosecutor doesn’t give written notice under s 177(5) until immediately before the certificate would otherwise be admitted – but it does provide a means by which expert witness costs might (at least in some cases) be kept to a minimum for defendants (as well as the prosecution).