Breaking the chain of causation in English marine insurance law (Novus Actus Interveniens)

Abstract In English marine insurance law, an insurer’s liability is determined by identifying the proximate cause of a loss. When a subsequent, independent event intervenes after the insured peril, the question arises whether the chain of causation has been broken. This is framed through the doctrine of novus actus interveniens . This article argues that the doctrine has no independent existence in marine insurance law, being entirely subsumed by the proximate cause inquiry under the Marine Insurance Act 1906 (MIA 1906). This subsumption produces both clarifying and complicating effects on its application. On the clarifying side, the proximate cause framework, which prioritises efficiency and predominance over strict temporal sequence, provides a more coherent and commercially grounded basis for assessing intervening events than the tort-derived novus actus label suggests. On the complicating side, however, the absence of an independent doctrine creates uncertainty in cases involving human intervention, concurrent causes of equal efficacy, and the allocation of loss between insured and excluded perils. By tracing the evolution of the proximate cause doctrine from its early temporal formulations through case law, this article clarifies when the causal chain is maintained or disrupted and highlights the unresolved doctrinal questions.