Definition - What does Supervening Cause mean?
A supervening cause is a cause of an injury, or of damage that comes after the initial set of events has already been put into place, but without which the harm could not have taken place.
In the context of the law, the person responsible for the supervening cause can be liable for the harm as opposed to the person who created the proximate cause.
Justipedia explains Supervening Cause
Often, there are multiple causes that go into harm being caused. For example, if a truck driver doesn't tie his load down and the products start spilling onto the highway, this could be a proximate cause. However, if a person behind the truck swerves unnecessarily far into oncoming traffic and causes an accident, this would be a supervening cause. In order to find out who would be fully liable for the damage caused by the accident, a court case would most likely have to ensue.