Latin for 'a new action intervening'.

A term in law for an action that breaks the chain of causation. This can come about if the victim does something aside from what could be considered a reasonable response to the situation and that has some contributing factor to the incident. If the incident could not be reasonably forseen as happening without the action of the victim or a third party (and therefore the action could not be reasonably forseen either), then this action is a novus actus interveniens.

For example, if a car stereo switches on at full volume, and in their surprise the driver slams their foot on the accelerator, this action would be a novus actus interveniens - it could not be reasonably forseen that such a defect would cause the car to crash, had the driver not put his foot down.