Court case[1893] 1 QB 673

A fire broke out on the plaintiff's land. Fire-brigade men were already at work extinguishing it. The defendant, in good faith and wishing to help, entered the plaintiff's land and joined in the efforts to put out the fire. The plaintiff, as the person in possession of the land, sued him for trespass to it. The defendant pleaded that his entry was justified by the necessity of extinguishing the fire, and that he had entered honestly with the sole object of helping to save the property.

The court held the defendant liable for trespass. The fire was already being dealt with by the persons whose business it was to put it out, and the defendant's entry was not necessary for the protection of the property; his good faith and his wish to help did not convert an unnecessary entry into a justified one. Necessity could not be pleaded where the interference was not required by the circumstances. The defence depends on an objective need for the defendant's own intervention; a volunteer who intervenes where the danger is already being met by those responsible acts at his own risk.