Legal Definitions - Public necessity

Public necessity is a legal defense that can be used when someone interferes with another person's property during an emergency, but does so to prevent a much greater harm to the entire community or a significant portion of society.

Essentially, it allows an individual or government entity to trespass on or even damage private property if their actions are absolutely necessary to protect the public good from an imminent and severe danger. If this defense is successfully argued, the person who interfered with the property is not held responsible for any damages caused, because their actions were deemed essential to avert a larger catastrophe.

• Example 1: Wildfire Containment

  Imagine a massive wildfire rapidly approaching a residential neighborhood. Firefighters, to prevent the blaze from engulfing hundreds of homes and endangering lives, decide to intentionally demolish a single, unoccupied cabin located on private land at the edge of the fire's path. This action creates a crucial firebreak that successfully stops the fire from spreading into the community.

  Explanation: The firefighters technically trespassed by destroying private property (the cabin). However, their action was an emergency measure taken to protect the entire community from the much greater harm of widespread destruction and potential loss of life. If sued for trespass, they could use public necessity as a defense, absolving them of liability for the cabin's destruction.

• Example 2: Flood Diversion

  During an unprecedented flood, a river threatens to overflow its banks and inundate a large town, potentially causing billions in damage and displacing thousands. Local emergency management officials, after exhausting all other options, order the controlled breach of a section of a private farm's levee, diverting the floodwaters into an uninhabited agricultural field. This action successfully saves the town from catastrophic flooding.

  Explanation: The officials intentionally damaged private property (the levee) and caused water to trespass onto the farmer's land. This was done in an emergency to protect the public (the town's residents and infrastructure) from a far greater disaster. The defense of public necessity would likely protect the officials from liability for the damage to the farm.

• Example 3: Pandemic Emergency Facility

  In the midst of a severe public health crisis, a government agency needs to rapidly establish a temporary emergency hospital due to overwhelming patient numbers. With no suitable public facilities immediately available, they commandeer a large, privately owned event hall, converting it for medical use without the owner's immediate consent. This action allows thousands of critically ill patients to receive care, preventing a collapse of the healthcare system and widespread fatalities.

  Explanation: The government agency trespassed by taking possession and modifying private property (the event hall) without permission. However, this was an emergency measure to protect the health and safety of the entire community during a pandemic. Public necessity would serve as a defense against a trespass claim, as the action was taken to prevent widespread illness and death.