It is based on the legal maxim “Salus populi suprema lex esto” which means the welfare of the people shall be the supreme law. It gives the State or an individual a privilege to take or use the property of another. It is of two types, private necessity and public necessity.
Private necessity – It is the use of another’s property for private reasons.
Vincent v. Lake Erie Transportation Co. [109 Minn. 456] – Defendant was at the dock of the plaintiff to unload cargo from the steamship owned by the defendant. An unusually violent storm developed. Lake Erie was unable to leave the dock safely and deckhands for the steamship instead tied the Reynolds to the dock, continually changing ropes as they began to wear and break. A sudden fierce wind threw the ship against the dock significantly damaging the dock. The court held that a private necessity may require one to take or damage another’s property, but compensation is required.
Public necessity – It is the use of private property by a public official for a public reason.
Surocco v. Geary (58 Am Dec 385) – San Francisco was hit by a major fire. The plaintiff, Surocco, was attempting to remove goods from his home while the fire raged nearby. The defendant and mayor of San Francisco, Geary, authorized that the plaintiff’s home be demolished to stop the progress of the fire and to prevent its spread to nearby buildings. Surocco sued the mayor claiming he could have recovered more of his possessions had his house not been blown up. The court allowed the defence of public necessity as any delay in blowing up the house to allowing plaintiff to remove more of his possessions would have made blowing up the house too late.