Definition
A new intervening act that breaks the chain of causation between the defendant's negligent act and the plaintiff's harm — freeing the defendant from liability if the intervening act was unforeseeable and was the real or dominant cause of the harm.
Novus actus interveniens (Latin: 'a new intervening act') is the principle that an unforeseeable, independent act that intervenes between the defendant's negligence and the plaintiff's harm may break the causal chain — making the intervening act the legal cause of the harm rather than the defendant's original negligence. Elements: (a) there must be an act of a third party or the plaintiff themselves; (b) the act must be independent and unforeseeable (not a natural and probable consequence of the defendant's negligence); (c) the intervening act must be the real or dominant cause of the harm. If the intervening act was foreseeable as a likely consequence of the defendant's negligence, there is no novus actus — the defendant remains liable.
Statutory Definition
No statutory provision — novus actus interveniens is a common law principle of causation in tort law. Section 104, Bharatiya Sakshya Adhiniyam (BSA), 2023 (formerly Section 104 IEA) — relationship between fact proved and fact in issue — provides the statutory foundation for causal analysis in Indian evidence law. For criminal law causation, the BNS uses causation principles in determining liability for consequences of criminal acts.
Etymology & Origin
Latin 'novus' (new) + 'actus' (act, from 'agere' — to do) + 'interveniens' (intervening, present participle of 'intervenire' — to come between). 'A new act coming between' — a fresh act that inserts itself into the causal sequence and breaks the connection between the original wrong and the resulting harm.
Full Legal Analysis
Novus Actus Interveniens: The Chain-Breaking Intervention
Causation in tort law is rarely simple. Between a defendant’s negligent act and the plaintiff’s harm, there may be many intermediate events — acts of third parties, decisions by the plaintiff, natural events. Not all of these break the causal chain; only unforeseeable, independent acts that become the real cause of harm operate as a novus actus. The principle preserves fairness: a defendant should not be held liable for harm caused by unpredictable intervening events they could not have guarded against.
Test for Novus Actus: Foreseeability
The key test: was the intervening act reasonably foreseeable as a probable consequence of the defendant's negligence? (a) Foreseeable intervention — no novus actus: A driver negligently knocks a pedestrian into the road; another car (predictably using the road) strikes the pedestrian. The second car’s action is foreseeable — no novus actus. The original driver remains liable. (b) Unforeseeable intervention — novus actus: A driver negligently injures a pedestrian; a hospital treats the pedestrian negligently and causes additional harm. If the hospital’s negligence was gross and unforeseeable, it may break the causal chain — the driver is not liable for the additional harm caused by the hospital’s independent negligence.
Plaintiff’s Own Act as Novus Actus
The plaintiff’s own unreasonable act may also constitute a novus actus interveniens — breaking the chain and leaving the defendant without liability (or reducing it through contributory negligence). Example: A negligently creates a danger; B, fully aware of the danger, deliberately walks into it for reasons of their own. If B’s decision was wholly unreasonable and unforeseeable, B’s own act may break the chain. However, if the defendant’s negligence specifically created the risk that the plaintiff then encountered (the 'egg-shell skull' rule — take your victim as you find them), the plaintiff’s own vulnerability is not a novus actus.
“Novus actus interveniens is the limit of responsibility — a defendant cannot be held accountable for every consequence that follows their negligence through unpredictable chains of events. The law must draw a line where the connection between act and harm is so attenuated, so dependent on independent human choices, that it would be unfair to extend liability that far.”
