Legal Definitions - causa sine qua non

Definition: Causa sine qua non is a Latin term that means "necessary cause." It refers to the cause without which the thing cannot be or the event would not have occurred.

Example: If a person is hit by a car and dies, the cause of death is the impact of the car. However, if the person would not have died if they had been wearing a seatbelt, then the seatbelt is the causa sine qua non of the person's death.

This example illustrates that the seatbelt is the necessary cause of the person's death. Without the seatbelt, the person would not have died from the impact of the car. Therefore, the seatbelt is the causa sine qua non of the person's death.