Legal Definitions - efficient proximate cause

Efficient proximate cause refers to the primary, dominant, or most direct cause that sets in motion a chain of events leading to a particular injury or damage. It is the cause without which the injury or damage would not have occurred, even if other contributing factors were present. In legal contexts, especially in insurance claims or tort law, identifying the efficient proximate cause helps determine responsibility or coverage by singling out the most significant factor among several potential causes.

• Example 1: Automobile Accident

  A driver, distracted by their phone, swerves into another lane and collides with another vehicle. The other vehicle was traveling slightly above the speed limit, but not excessively. In this scenario, the distracted driver's action of swerving due to phone use would be considered the efficient proximate cause of the accident. While the other driver's slight speeding might have been a contributing factor, the collision would not have occurred without the first driver's direct and negligent action of swerving into the lane.

• Example 2: Property Damage and Insurance

  A homeowner's basement floods after a severe thunderstorm causes a nearby river to overflow its banks. The homeowner's insurance policy covers damage from "burst pipes" but specifically excludes damage from "flooding." Although the homeowner had a small, pre-existing crack in their basement foundation, the overwhelming volume of water from the overflowing river was the direct and dominant force that caused the extensive flooding and damage. Therefore, the river overflowing due to the thunderstorm would be identified as the efficient proximate cause, leading to the conclusion that the damage is likely excluded under the policy's flood exclusion, despite the minor pre-existing crack.

• Example 3: Construction Defect

  A building contractor uses substandard concrete in the foundation of a new commercial building, against code requirements. Five years later, a minor earthquake, which would typically cause no structural damage to a properly constructed building, causes significant cracks and structural instability in the building's foundation. While the earthquake was the immediate trigger for the damage, the use of substandard concrete by the contractor is the efficient proximate cause. The building would have withstood the minor earthquake without significant damage had the foundation been built correctly, making the faulty construction the dominant factor leading to the structural failure.