The recent decision in Culhana v State of New South Wales (NSW Police Force) & Others [2024] NSWPIC 257 provides critical insights into the treatment of complex causation in workers' compensation claims. It highlights the Personal Injury Commission's (PIC) pragmatic approach to linking psychological injuries to severe physical conditions, even when causation is multifactorial. For plaintiff lawyers, this decision demonstrates the expanding scope for claims where psychological injuries act as gateways to secondary physical conditions. This case serves as a reminder that a commonsense approach to causation—rather than requiring direct, linear links—can lead to successful outcomes for workers and their families.
Background
The case arose following the death of Craig Stockwell, a New South Wales police officer who developed post-traumatic stress disorder (PTSD) as a result of his employment. The NSW Police Force, as the first respondent, accepted liability for his PTSD. However, a more contentious issue arose when Mr Stockwell was later diagnosed with Barrett's oesophagus and adenocarcinoma, which ultimately caused his death on 27 November 2022.
His de facto partner, the applicant, sought compensation, arguing that the PTSD materially contributed to the conditions leading to Mr Stockwell's death. The respondent denied this connection, contending that the fatal condition was caused by other unrelated factors, such as acid reflux, smoking, and alcohol use.
The PIC was tasked with determining whether PTSD caused or materially contributed to Barrett's oesophagus, adenocarcinoma, and subsequent death. The decision provides crucial guidance for workers' compensation cases involving multifactorial causation.
The Personal Injury Commission's approach
The PIC applied a commonsense approach to causation, acknowledging that workplace injuries rarely result in straightforward causal chains. Instead, the Commission considered all available evidence to evaluate the relationship between PTSD and Mr Stockwell's physical conditions.
Key considerations in causation
Multifactorial causes
Expert evidence confirmed that Mr Stockwell's Barrett's oesophagus and adenocarcinoma resulted from multiple factors, including:
- Stress related to PTSD (causing increased gastric acid production and reflux),
- Smoking (a known carcinogen),
- Alcohol consumption,
- Underlying gastroesophageal reflux disease (GORD).
Despite the presence of non-work-related contributors, the medical consensus was that stress linked to PTSD was a material factor in the progression of Mr Stockwell's conditions.
The material contribution test
The Commission relied on the established principle from Bonnington Castings v Wardlaw [1956] AC 613, which states that a claimant need not prove a single dominant cause of injury. Instead, it is sufficient to demonstrate that the workplace injury materially contributed to the overall harm. The PIC emphasised that the material contribution test is particularly important in cases involving multifactorial causation, where it may be impossible to isolate any single cause.
Balancing evidence on the balance of probabilities
While the respondents argued that factors like smoking and alcohol were the predominant causes of Mr Stockwell's adenocarcinoma, the PIC determined that such factors did not negate the significant role of PTSD. On the balance of probabilities, PTSD was found to be a material contributor to Barrett's oesophagus, the development of adenocarcinoma, and Mr Stockwell's death.
Legal and practical implications for workers
The PIC's decision in this case carries important implications for plaintiff lawyers advocating for workers with psychological and secondary physical injuries:
1. Strengthening claims with expert evidence
Expert medical evidence played a pivotal role in establishing causation in this case. All medical experts agreed on the multifactorial nature of Barrett's oesophagus and adenocarcinoma. However, they also identified stress as a contributing factor through its impact on gastric secretions.
For plaintiff lawyers, obtaining clear, detailed medical opinions is essential. Experts should address:
- How a workplace injury (e.g., PTSD) contributed to the development or progression of a condition,
- The role of secondary conditions (e.g., GORD) in the causal chain,
- The interaction between psychological injuries and physical health.
Lawyers must ensure that expert reports present a cohesive narrative linking the workplace injury to the eventual harm.
2. Utilising the material contribution test
Culhana reaffirms that plaintiffs do not need to establish that a workplace injury was the sole or predominant cause of their condition. Instead, the focus should be on proving that the injury materially contributed to the harm.
This principle is particularly significant in cases involving:
- Psychological injuries leading to physical manifestations,
- Conditions with multiple contributing factors (e.g., lifestyle, genetics, pre-existing conditions).
Lawyers should emphasise the material contribution standard when responding to arguments that non-work factors diminish or negate the causal link to employment.
3. Recognition of psychological injuries as gateways
The PIC's decision highlights the potential for psychological injuries, such as PTSD, to act as gateways to serious physical conditions. Stress-related illnesses, like GORD, can evolve into more severe conditions, including cancers.
For workers suffering from mental health injuries, this case provides a foundation for arguing that psychological harm can have far-reaching physical consequences.
Plaintiff lawyers should explore these connections fully when building claims, particularly in cases where employers accept liability for psychological injuries but contest subsequent physical conditions.
4. The importance of a commonsense approach
The PIC's reliance on a commonsense evaluation of the causal chain reinforces the need for practical arguments that reflect real-world experiences. Lawyers should:
- Present evidence holistically, avoiding overemphasis on isolated causes,
- Highlight the interconnectedness of mental and physical health,
- Use real-life analogies and commonsense reasoning to frame complex causation arguments.
Broader lessons for the workers' compensation framework
The Culhana decision reflects the evolving understanding of causation in workers' compensation law. It demonstrates that workplace injuries, particularly psychological injuries, cannot be viewed in isolation. Stress-related illnesses are often the starting point for more severe conditions, creating opportunities for plaintiff lawyers to secure compensation for workers and their families.
Key takeaways include:
- Recognition of the modern workplace – high-stress environments, particularly in roles like policing, can have profound long-term health effects. Employers and insurers must acknowledge the cumulative impact of psychological injuries.
- Holistic medical assessments – medical practitioners play a critical role in connecting psychological harm to physical health outcomes. A multidisciplinary approach to medical evidence can strengthen claims involving complex causation.
- Avoiding an overly technical approach – the PIC's commonsense reasoning underscores the importance of viewing workers' experiences realistically. An overly technical or rigid approach to causation risks unjust outcomes for injured workers.
For plaintiff lawyers, this case serves as a blueprint for advocating on behalf of workers whose psychological injuries have far-reaching physical consequences. It reaffirms the importance of expert evidence, highlights the flexibility of the material contribution test, and underscores the need to frame causation arguments holistically. As psychological injuries become increasingly recognised in workers' compensation law, Culhana provides a valuable precedent for securing justice for injured workers and their families.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
