When one commits an error in understanding. Mistake may be committed by a person and it may be of two kinds:
(i) Mistake of law – a person cannot take the defence that she was not aware that a particular law existed which made her actions wrong in nature. For eg. laws on assault exist in both civil and criminal branch of law. So, A can’t take the defence of Mistake of Law when she assaulted someone by pleading her unawareness about the existence of such laws.
(ii) Mistake of fact. – A person can’t avoid a tortious liability when she commits a tort by believing a set of facts to be true, when they were not. An excellent example is – in the case Ransom v. Kitner, (1888) the defendant killed the plaintiff’s dog while he was hunting for wolves. The dog of plaintiff had striking resemblance to a wolf. The defendant was held liable for his act. When a person has committed some act by mistake, it can’t be said that she has committed a wrongful act. If a plaintiff moves an action with malice or wrongful motive then in such circumstances, mistake may be taken as a good defence.
Sometime, even an innocent person faces prosecution, but the prosecutor incurs no liability unless he has acted both maliciously as well as without reasonable cause. That’s why a mistaken arrest of an innocent person on suspicion of felony is not actionable; if the felony has actually been committed, and there is a reasonable ground for believing that the person arrested is guilty of it.
Sometimes, intentional injury to a person or property may be caused yet the defendant may not be held liable if he
pleads the defence of ‘necessity’. The defence of ‘necessity’ originates from the maxim ‘Salus populi supreme lex‘ which says the welfare of the people is the supreme law. This maxim has got the implied assent of every member of the society, that the welfare of the community comes first compared to individual’s welfare i.e., the welfare of community is paramount and for that individual’s property, liberty and life shall, under certain circumstances be placed in jeopardy or even sacrificed for public welfare.
In the year, 1507, Kingsmill, J.1 observed-“that the violation of another man’s rights could be justified on the ground that the act was necessary to the common well, as in case of fire to take goods out of a house to save them, to pull down a house to save other houses and in time of war to enter another man’s land to make a bulwark in defence of the king and the realm.”
There are some cases in which decision has been given under the defence of necessity-
(a) Deway v. White.-destruction of a building made ruinous by fire to prevent its collapse into the highway.
(b) Saltetre case, (1605) -here a house was pulled down which was on fire to prevent the spread of fire to the property of others.
(c) Kirk v. Gregory, (1876) – in this case A died in a state of delirium tremens. His servants were feasting and drinking in the house. B, sister-in-law of A, removed the jewellery of A from the room where he lay dead and kept it in another room for the sake of safety. But, it was her mistaken belief and the Jwellery got stolen from that room. The court remarked, ‘it is a defence that the act was done for the preservation or protection of the property of the person, provided there was reasonable necessity for the act’. B was held liable to A’s executor for trespass to the jewellery because there was no proof that her interference was reasonably necessary.
The Parliament enacts the law at the same time, it has also the power to reverse any principle of common law. Any act or omission tortious under the common law may be specifically made legal by a statute and in that respect, statutory authority is a defence. This was discusses in the case Chandram Nagaram Rice & Oil Mills Ltd., Gaya v. Municipal Commissioner of Purulia.
In Bhogilal v. Municipality of Ahmedabad, Municipality of Ahmedabad demolished a wall of plaintiff under their statutory powers. The roof of plaintiff also collapsed in the process. On the points raised by the plaintiff, the court held that no suit will lie against the defendant, as they have carried out their duty under statutory powers although the plaintiff has suffered injury. The power (statutory) has been exercised with judgment and caution.
In Chandram Nagaram Rice & Oil Mills Ltd., Gaya v. Municipal Commissioner of Purulia, 1944, The plaintiff loaded 1000 canisters of mustard oil in a van belonging to Eastern Railways from Gaya to be sent to Purulia, West Bengal. As soon as, it reached Purulia, the local Municipal Commissioner seized the consignment. The seizure was to check the quality of the oil whether it was good or bad. After seizure of oil, it was loaded in a scavenger’s truck by mehtars (sweepers). The plaintiff brought a suit against the defendant on the ground that it has caused damages to their finances as well as reputation (branded name). The Court observed that the defendant in order to prevent beri-beri a disease within the municipality acted in haste and that the action of the municipality, if not actuated by malice or a result of conspiracy was certainly unreasonable and negligent. Justice Varma observed-“if a person is exercising his rights under a statute he is not liable unless it is proved that he acted unreasonably and negligently
Imperative Authority :-
Some powers which are conferred by the legislature for a particular thing to be done regardless of whether it inflicts an injury upon another person, it is called as absolute, mandatory or imperative authority. In case of harm, it is being covered by the authority e.g., to construct the railway line, there may be need of acquiring private land. But, in such cases the land owner will be suitably compensated. But, running a train without causing noise or vibration is impossible and for such complaint there is no remedy. If, the legislature has authorized certain act and the authority given is imperative, no action would lie against the person who has the statutory authority to do the act, provided it is done without negligence. This statutory authority not only extends to the act itself, but to all its necessary consequences.