Legal Definitions - nova causa interveniens

In legal terms, nova causa interveniens (Latin for "new intervening cause") refers to an event or action that occurs after an initial wrongful act or omission, and which is so significant and unforeseeable that it breaks the chain of causation between the original act and the resulting harm. When a court finds a nova causa interveniens, it means that the original wrongdoer is no longer considered legally responsible for the ultimate harm, because the new, independent event is deemed the true cause.

Here are some examples to illustrate this concept:

• Example 1: Medical Malpractice Following an Accident

  Imagine a driver, Mr. Smith, negligently runs a red light and collides with Ms. Jones's car, causing her a broken leg. Ms. Jones is taken to the hospital, where, due to a severe and unforeseeable error by the surgeon (e.g., operating on the wrong leg), she suffers permanent damage to her healthy leg.

  In this scenario, Mr. Smith's initial negligence caused the broken leg. However, the surgeon's gross medical error, which caused damage to the healthy leg, could be considered a nova causa interveniens. While Mr. Smith would still be responsible for the initial broken leg, the surgeon's independent and unforeseeable mistake might relieve Mr. Smith of liability for the additional, distinct harm to Ms. Jones's healthy leg. The surgeon's action broke the direct causal link between Mr. Smith's driving error and the injury to the healthy leg.

• Example 2: Negligent Storage and Unforeseeable Theft

  A construction company leaves a large, expensive piece of equipment unsecured and clearly visible on a public street overnight, violating company policy and local ordinances. While this is negligent, the equipment is then stolen by a highly organized criminal gang using sophisticated tools and planning, an event far beyond typical opportunistic theft.

  Here, the construction company's negligence in leaving the equipment unsecured created a risk. However, the highly sophisticated and unforeseeable theft by a criminal gang might be considered a nova causa interveniens. The court might determine that the specific, elaborate nature of the theft was an independent event that broke the direct causal link between the company's simple negligence and the loss of the equipment, especially if the theft was not a foreseeable consequence of merely leaving it unsecured.

• Example 3: Defective Product and Intentional Tampering

  A toy manufacturer produces a batch of toys with a minor design flaw that could, in rare circumstances, cause a small, non-injurious part to detach. Before any such detachment occurs, a disgruntled former employee intentionally and maliciously tampers with several of these toys, inserting sharp objects into them, which then cause severe injuries to children.

  The manufacturer's initial design flaw is a form of negligence. However, the former employee's deliberate and malicious act of inserting sharp objects is a nova causa interveniens. This intentional tampering is an unforeseeable and independent act that directly caused the severe injuries, breaking the causal chain from the manufacturer's minor design flaw to the actual harm. The manufacturer would likely not be held responsible for the injuries caused by the intentional tampering.