Breaking the chain of causation: Ironmonger v Gunnedah Shire Council

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Louise Cantrill, Partner and Mason Thomas, Lawyer

The case of Ironmonger v Gunnedah Shire Council [2021] NSWPIC 48 follows a series of authorities in finding substandard medical care may not break the chain of causation so as to excuse negligence of an earlier tortfeasor. To achieve this the substandard care must be so “inexcusably bad” and unwarrantable so as to disturb the sequence of events. Otherwise, it will be considered a foreseeable consequence for which the first tortfeasor remains liable.


Mr Brian Ironmonger (the deceased) suffered a psychological injury as a result of work, deemed to have occurred on 28 February 2017. He returned home that day and attempted suicide by way of overdose. He was taken to Gunnedah Hospital and was later transferred to Tamworth Base Hospital (the Hospital), where he died on 10 March 2017.

On 16 January 2018, the Coroner concluded the deceased’s cause of death was pulmonary embolism, a blockage in one of the pulmonary arteries in the lungs caused by blood clots that travel to the lungs from deep veins in the legs (deep vein thrombosis). The Coroner also found his morbid obesity to be an antecedent cause. At the time of his admission the deceased weighed 186kg.

Mr Robert Ironmonger (the applicant), the deceased’s father, brought an application for death benefits compensation under the Workers Compensation Act 1987.

Gunnedah Shire Council (the respondent) disputed liability for the claim, alleging the treatment received by the deceased at the Hospital was so inexcusably bad that the death resulted from the treatment post overdose, and not the injury. As such, the death was unrelated to his employment for the purposes of compensation

Understanding novus actus interveniens

In determining causation under the Workers Compensation legislation, the incapacity must be shown to have resulted from the work injury. In this case, the applicant submitted the work injury caused the deceased to overdose, which was a necessary condition for the chain of events leading to his pulmonary embolus and death, including prolonged bed rest, intubation and ventilation.

Causation can, however, be nullified where a new, unforeseeable or extrinsic cause is shown to have disrupted the causal connection such that the harm has resulted from a later negligence more proximate to the incapacity/death. This is described as a novus actus interveniens, said to “break the chain of causation which would otherwise have resulted from an earlier wrongful act”.[1]

The respondent served expert evidence which found “there was unacceptable sub-therapeutic prophylaxis and unacceptable lack of appropriate testing and treatment when pulmonary embolism considered by medical staff” at the Hospital. In particular, the respondent submitted the Hospital failed to adjust the dosage of anticoagulant medication in consideration of the deceased’s morbid obesity, thereby underdosing him with the standard dose.

The applicant submitted the standard dose for prophylaxis is independent of weight and the deceased developed fatal pulmonary embolism despite appropriate prophylactic treatment.

Ms Jane Peacock, Member of the Personal Injury Commission found in favour of the applicant, stating she was “not satisfied on the balance of probabilities that the treatment afforded by Tamworth Base Hospital was so inexcusably bad as to break the chain of causation between injury on 28 February 2017 and death on 10 March 2018.” As such, the death benefit compensation was payable to the legal personal representative of the deceased’s estate.

Closing remarks

While this case upheld the right of the plaintiff to recover his full losses from Gunnedah Shire Council, it remains to be seen whether Gunnedah Shire Council might otherwise have a right to seek contribution for the amount paid out to the plaintiff, at least in terms of general principles, if not in this specific circumstance.

[1] March v Stramare (E & MH) Pty Ltd (1991) 171 CLR 506, [23] (Mason CJ).

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