Another pathway for the admissibility of expert reports

In the usual course, opinion evidence is inadmissible in a court proceeding.¹ The Evidence Act at s 79 provides an exception for the opinion of an expert in their field of specialised knowledge. The admissibility requirements are strict, and can often be contentious. A recent decision of the Supreme Court of New South Wales has identified a stand-alone pathway for expert evidence through expert certificates.

In Director of Public Prosecutions (NSW) v JS [2025] NSWSC 1172, the DPP appealed a decision of the Children’s Court, where a magistrate had acquitted a juvenile (JS) of unauthorised possession of a pistol under s 7(1) of the Firearms Act 1996 (NSW).

Investigators had obtained a report from a firearms expert who observed videos of the accused holding what appeared to be a pistol. The expert then opined on the nature and type of that firearm.

The prosecution filed that reportwith a certificate under s 177 of the Evidence Act.

Section 177 of the Uniform Evidence Act

Sub-s 177(1) provides:

Evidence of a person’s opinion may be adduced by tendering a certificate ( expert certificate ) signed by the person that—

        (a)     states the person’s name and address; and

        (b)     states that the person has specialised knowledge based on his or her training, study or experience as specified in the certificate; and

        (c)     sets out an opinion that the person holds and that is expressed to be wholly or substantially based on that knowledge.

Sub-section (5) provides that the party on whom the notice is served (in this case, JS) may give written notice requiring the expert to be available for cross-examination, which then renders the expert certificate inadmissible: s 177(6). JS had made no such objection.

Is section 177 a stand-alone basis of admissibility?

The key question for the Supreme Court was whether the opinion subject of a certificate issued under s 177 of the Evidence Act also needed to comply with the usual requirements for expert evidence (e.g., s 79), or whether compliance with s 177 alone was sufficient for admissibility.

Payne JA held that a s 177 certificate does not need to comply with the usual expert‑evidence rules so long as the certificate meets the formal requirements of s 177 and no written objection was filed.²

This means that s 177 is an alternative – and less stringent – pathway for admitting opinion‑like material. Where its conditions are met, the certificate is admissible even if it does not comply with the ordinary rules governing expert opinion evidence.³

The take-away for practitioners

On the prosecution side, this new pathway can streamline the admissibility of expert opinions. It is likely to be of greater utility for opinions that are unlikely to be controversial. It is doubtful whether this pathway could be practically used to render admissible opinion that would plainly be inadmissible under s 79. It is a process that could be particularly useful in summary regulatory prosecutions. As Payne JA said, s 177 ‘is intended to facilitate proof of relatively routine matters calling for expert opinion.’⁴

On the defence side, careful attention to prosecution documents is required to identify when a s 177 certificate has been issued. Consideration should be given to prompt, written objection to that certificate if the opinion will (or even might) be challenged in a contested hearing.

1. Evidence Act, s 76. ↩︎
2. See, especially, [57]. ↩︎
3. At [63]-[64]. ↩︎
4. At [64]. ↩︎