Novus actus interveniens is a Latin phrase which translates as ‘new act intervenes’. It refers to an intervening act or omission which breaks the chain of causation, thereby relieving an individual of liability.
Consider the following scenario: A is beaten up by B and ends up in hospital, in need of treatment. His injuries are serious but not life-threatening, and he is expected to make a full recovery.
During the course of his treatment, one of his doctors, C, turns up to work drunk and makes a mistake which leads to A’s death a few hours later.
In this scenario, B would not be held responsible for A’s murder as the negligent actions of C were significant enough to have acted as a novus actus interveniens, breaking the chain of causation from B’s assault to A’s death.