Judgment of: Priestley JA, Powell JA and Heydon JA
Summary
Makita (Australia) Pty Ltd v Sprowles (‘Makita’)[1] is the leading New South Wales Court of Appeal authority on the admissibility and reliability of expert opinion evidence. Heydon JA’s judgment sets out what an expert opinion should disclose to be admissible and carry weight. The evidence must be wholly or substantially based on the witness’s specialised knowledge, founded on identified and proved facts, and supported by a reasoning process that the expert exposes so the court can evaluate it. An opinion that states a conclusion without demonstrating how it was reached is of little weight and may even be inadmissible.
Background Facts
Ms Vicki Sprowles was employed by Makita (Australia) Pty Ltd. On 30 June 1986, Ms Sprowles slipped and fell while using a stairway at her workplace that provided access between a rooftop carpark and the offices, sustaining personal injury. She sued her employer in negligence, alleging that Makita had failed to provide a safe means of access to the office because the stairs were dangerously slippery.
At first instance, Ms Sprowles relied on expert testimony provided by Associate Professor Morton, a physicist specialising in the investigation of slipping accidents. He measured the coefficient of friction of the stair treads and of the flat red shoes Ms Sprowles said she had been wearing at the time of the accident. He conducted his tests in December 1995, about 9½ years after the accident, and concluded that the stair treads lacked an adequate non-slip finish and were sufficiently slippery to be dangerous for a person wearing common footwear. The trial judge, James J, accepted that opinion and entered a verdict in favour of Ms Sprowles, finding that the stairs were dangerously slippery, that Makita had thereby failed to provide a safe means of access, and that this failure caused her fall.
Makita appealed to the New South Wales Court of Appeal, where the matter was heard before Priestley, Powell, and Heydon JJA.
Issues
Whether Associate Professor Morton’s expert evidence on the slipperiness of the stairs, relied on by the trial judge, was admissible and sufficiently reliable to support the findings that the stairs were dangerously slippery, that the employer had breached its duty to provide a safe means of access, and that this breach caused Ms Sprowles’ fall.
Decision
The Court of Appeal allowed the appeal and set aside the judgment. Heydon JA held that Associate Professor Morton’s opinion should not have been accepted, because it did not satisfy the conditions for admissible and reliable expert evidence. Specifically, the expert:
- Did not adequately identify and prove the facts underlying his opinion;
- Did not explain the reasoning process connecting those facts to his conclusion that the stairs were dangerous; and
- Reached a conclusion that was not consistent with the data presented, which showed the treads met the relevant Australian Standard (AS 3661.1) for slip resistance.
The reliability of the opinion was further undermined because the testing took place some 9½ years after the accident, and the stairs had been used by the plaintiff and others without similar incidents occurring. Once Associate Professor Morton’s opinion was rejected, there was no proper basis for the findings of breach and causation, and the claim failed for want of a proper evidentiary foundation to establish a breach of duty of care.[2]
Key Points for an Expert/Specialist Witness
The following requirements must be satisfied for expert opinion evidence to be admissible and carry weight:[3]
- There must be a recognised field of specialised knowledge, whether scientific, technical, or otherwise.
- The witness must have become an expert in an identified aspect of that field through training, study, or experience.
- The opinion must be wholly or substantially based on the witness’s specialised knowledge.
- The facts on which the opinion is based must be clearly identified. Facts observed by the expert must be admissibly proved by the expert, and any assumed or accepted facts must be proved by other evidence.
- Those facts must form a proper foundation for the opinion expressed.
- The expert must demonstrate the reasoning or intellectual basis by which the opinion was reached, explaining how the specialised knowledge was applied to the facts to arrive at the stated conclusion.
- All of these matters must be made explicit, so that the court can determine whether the opinion truly rests on specialised knowledge.
- If the court cannot be satisfied that the opinion is based on specialised knowledge, it is inadmissible, or at best, of diminished weight.
- The expert must not stray into speculation, personal inference, or assessments of credibility. As Gleeson CJ observed in HG v The Queen, such material may amount to “a combination of speculation, inference, personal and second-hand views” that goes beyond legitimate expertise.[4]
Subsequent Consideration
The principles in Makita have been applied and refined by later authority. In Dasreef Pty Ltd v Hawchar (‘Dasreef’)[5], the High Court considered the admissibility of expert opinion under s 79 of the Evidence Act 1995 (NSW), which permits expert opinion evidence where the witness has specialised knowledge based on training, study, or experience, and the opinion is wholly or substantially based on that knowledge. The Court cautioned against treating Heydon JA’s formulation in Makita as a rigid checklist of admissibility rules.[6] In jurisdictions that have adopted the Uniform Evidence Law, admissibility is governed by s 79 itself. However, the core requirement remains that the expert must identify the facts assumed or observed, identify the specialised knowledge relied upon, and explain how that knowledge was applied to reach the opinion expressed.
Queensland has not adopted the Uniform Evidence Law. Expert opinion evidence in Queensland is therefore governed principally by the common law. In Lang v The Queen[7], which was an appeal from Queensland, the High Court confirmed that the Makita and Dasreef principles concerning the admissibility of expert opinion apply equally at common law and under the Uniform Evidence Law.[8]
Implications
Makita remains important for both civil litigation and medico-legal practice. The later authorities have clarified how the principles operate in different evidence regimes, but the practical lesson for experts and specialist witnesses remains the same. A report must be:
- Factually grounded: The facts and assumptions are clearly identified and provable;
- Logically reasoned: Each conclusion is supported by a stated explanation of how it was reached; and
- Transparent and methodical: The reasoning process must be visible, traceable, and able to be tested.
Courts will not accept expert reports uncritically. An opinion that lacks an identified factual foundation or a demonstrable reasoning process may be excluded or given little weight, however eminent its author. For medico-legal experts in particular, this means a defensible report exposes the path from history, examination, and assumed facts through to diagnosis, causation, and impairment, not merely the conclusion reached.
[1] (2001) 52 NSWLR 705.
[2] Makita (n 1) [102] (Heydon JA); see also [21] (Powell JA).
[3] Makita (n 1) [85].
[4] (1999) 197 CLR 414, [41], quoted in Makita (n 1) [85].
[5] (2011) 243 CLR 588.
[6] Ibid [37].
[7] (2023) 278 CLR 323.
[8] Ibid [11].