Background
On 7 October 2016, a speedboat controlled by the defendant David Boyd collided with a jet ski carrying eight-year-old Luke Walmsley (a passenger) and operator Danielle Taylor on the Nerong River. Ms Taylor was killed; the plaintiff suffered injuries including an alleged traumatic brain injury. The plaintiff, now represented through his tutor grandmother Anita Walmsley, sued for damages. The defendant admitted breach of duty of care but disputes the quantum of damages, particularly the extent of any brain injury.
The parties obtained a joint single expert report from neuropsychologist Dr Louise Parry under the Uniform Civil Procedure Rules 2005 (NSW). Dr Parry concluded the plaintiff suffered only a moderate traumatic brain injury at most, with no continuing neurocognitive deficit attributable to the accident. She questioned the reliability of Mrs Walmsley’s reports about the plaintiff’s behavior and functioning. The plaintiff sought court leave under UCPR r 31.44 to adduce evidence from a second neuropsychologist, Dr Jamie Berry, citing deficiencies in Dr Parry’s assessment.
The Court’s Holding
Justice Elkaim granted the plaintiff leave to obtain and rely on a report from Dr Jamie Berry, subject to the condition that the plaintiff’s solicitors bear the cost of the assessment and report. The court found a sufficient basis to permit additional expert evidence, rejecting a rigid application of the single expert rule.
The judge identified several factors supporting leave: Mrs Walmsley (the tutor) would suffer a “legitimate sense of grievance” if precluded from advancing the case, potentially affecting her capacity to give instructions; there is a real dispute about the severity of the brain injury (mild, moderate, or severe), which materially affects the plaintiff’s future life and damages; competing expert opinion exists (Dr Mandalis had previously opined the injury was “at least moderate severity” and disagreed with Dr Parry’s assumption of pre-existing ADHD); and Dr Parry’s findings on brain injury extent depend partly on her assessment of Mrs Walmsley’s credibility, creating a conflict of evidence that the court (rather than a single expert) should resolve.
The court noted that while the defendant correctly observed that additional testing might require a two-year delay, a court can ultimately decide between competing expert opinions without requiring repetition. The judge also noted the plaintiff will turn 18 before trial, potentially negating the need for a tutor altogether, though this did not foreclose the application. Each party was ordered to pay its own costs of the motion.
Key Takeaways
- The single expert rule under UCPR r 31.44 is not absolute—courts retain discretion to grant leave where parties show an arguable basis for challenging the single expert’s conclusions.
- A tutor’s potential grievance at being unable to advance the plaintiff’s case through expert evidence, particularly where the single expert has questioned the tutor’s credibility, is a material consideration in the discretionary exercise.
- Where expert opinion depends partly on assessing credibility of lay witnesses (here, Mrs Walmsley’s reports), courts may permit additional expert evidence to allow the court itself to weigh competing assessments.
- Competing expert opinions within the existing record (here, Dr Mandalis’s view on injury severity and ADHD) support granting leave for further evidence on the same issue.
- Burden of cost can be imposed as a condition of granting leave for additional expert evidence.
Why It Matters
This decision clarifies that UCPR r 31.44, while designed to streamline expert evidence and avoid dueling experts, does not prevent courts from permitting multiple expert reports where a party demonstrates a legitimate basis for questioning the single expert’s conclusions. The judgment reflects tension between efficiency gains from joint experts and the risk that a single expert’s opinion might prevent a party from properly advancing its case, particularly where credibility assessments of lay participants affect the expert’s reasoning.
For practitioners in personal injury litigation, the decision signals that applications for leave to adduce additional expert evidence will succeed if there is an arguable factual or methodological challenge to the single expert’s opinion, or if excluding the further evidence would prevent a party (especially a vulnerable party represented through a tutor) from advancing its case at trial. The court’s balancing approach—granting leave but imposing cost conditions—offers a middle path between unrestricted expert proliferation and the risk of trial by single expert rather than trial by judge.