Legal Definitions - vis impressa

Vis impressa refers to the initial, originating act of force that sets in motion a chain of events ultimately leading to an injury. It is the fundamental, primary force that begins the sequence, as opposed to the immediate or direct force that directly causes the harm at the very end of the chain.

Here are some examples to illustrate this concept:

• Construction Site Accident: Imagine a construction worker improperly secures a heavy piece of scaffolding on a building. Weeks later, a strong gust of wind causes the poorly secured scaffolding to collapse, injuring a pedestrian walking below. The vis impressa in this scenario is the worker's initial act of improperly securing the scaffolding. This original, negligent act created the dangerous condition that, when combined with the wind (which might be considered a more immediate or proximate cause), led to the pedestrian's injury.

• Defective Product: Consider a toy manufacturer that designs and produces a batch of children's swings with a critical flaw in the chain links. Months after a swing is purchased and installed, a child is using it, and the defective link snaps, causing the child to fall and break an arm. The vis impressa here is the manufacturer's initial act of designing and producing the swings with a defective chain link. This original flaw was the foundational force that made the subsequent injury possible, even though the immediate cause was the chain link snapping during use.

• Physical Altercation: Suppose during an argument, one person forcefully shoves another. The person shoved loses their balance, stumbles backward several steps, and then trips over a loose rug, falling and hitting their head on a coffee table, resulting in a concussion. The vis impressa is the initial forceful shove. This original act of force directly initiated the sequence of events—losing balance, stumbling, tripping, and falling—that ultimately resulted in the concussion.