Introduction and Meaning
Necessity is a commonly used word and as defined by the Oxford English Dictionary, means something which is essential to have or is ‘necessary’. The simple meaning of necessity holds so much importance that it was the given the title of defence under the legal framework for the innocent to defend themselves in court. ‘Necessity’ is used in various fields of law, be it criminal or civil, each varying with the degree of crime committed. However, this article would mainly focus on the use of necessity under tort law. The doctrine first came into picture to help justify invasion of property during the time of war and excused trespass to save properties from fire, the very first example made to explain the principle of necessity.
Usually this concept is made as a defence to all kinds of trespass, and it has to be for the greater good of the public or should be in public interest. It is therefore, not just necessity but public necessity. Anything which is done for the private interests of the defendant would not be eligible to take the said defence as private necessity is no defence, although there have been exceptions for the same depending upon the case. A person/defendant when uses reasonable amount of force against an innocent person or property to evade an imminent danger for “public interest” would be permitted to use the defence of necessity.
For example, in the case of Leigh v. Gladstone, a woman was forcibly fed while she was a hunger striking prisoner, the defendant was allowed to take the defence of necessity against the action of battery (trespass to person). Similarly, in Cope v. Sharpe, the defendant had entered the plaintiff’s land in order to stop the spread of fire to an adjoining land (trespass to land), therefore the above defence was allowed here as it was considered to have been done to put an end to an imminent danger.
Difference between Self- defence and Necessity
Although self-defence and necessity seem to walk on the same path, there is a stark difference between them. When a person uses the defence of necessity, he/she is responsible for hurting an innocent who in the first place meant no harm to the him/her.
For example, in the case of Ploof v. Putnam, Ploof had tied his boat to the defendant’s dock in order to escape a storm but Putnam’s servant had untied the boat which led to its destruction and caused injury to the plaintiff. The court ruled in the favor of the plaintiff saying that it was necessary was him to commit trespass in situations like these, and hence is not liable under trespass to land. If we take this example, we see that Ploof did not have any intention of hurting Putnam but simply committed a tort out of necessity. This is a major difference between self-defence and necessity, because what happens in self-defence is that the person who uses this defence is responsible for hurting a wrongdoer or thinking it to be a wrongdoer and not an innocent.
Like in the case of People v. La Voie, a man’s car was pushed into an intersection by another man’s vehicle. Person from the second car got out and started approaching the defendant, due to which the defendant got out the car and shot him. The Colorado court in this matter said that, “when a person has reasonable grounds for believing, and does in fact actually believe, that danger of his being killed, or of receiving great bodily harm, is imminent, he may act on such appearances and defend himself, even to the extent of taking human life when necessary, although it may turn out that the appearances were false or although he may have been mistaken as to the extent of the real actual danger.” Had this been a case of necessity, the person who had caused the harm would know for sure that the person he had caused harm is innocent. Another difference is between these two principles is the amount of force required. Usually, necessity require a lot less force than self-defence making it the “lesser of the two evils”.
Contrast between Inevitable Accident and Necessity
Apart from self-defence, the defence of inevitable accident also seems to overlap with necessity. The difference here is that the harm which has been caused is an intended one in necessity, while under inevitable accident, the harm is caused even after putting in efforts to avoid it. The above mentioned cases for necessity prove the intention behind the person causing the harm, but for inevitable accident like in the case of Stanley v. Powell, both the parties were members of a pheasant shooting group. When the defendant was shooting one of the pheasants, the bullet bounced of an oak tree and injured the plaintiff. It was held to be an accident and defendant was not liable. Here, we could also see that apart from the harmed person being innocent, the intention of the one causing the harm should be present. 
Necessity’s relation to Medicine
The relation between necessity and medicine is also an important issue which is raised by many academicians. It is made clear by the courts that any medical treatment administered or prescribed by a doctor to an incapable person whose capacity is questioned, would be allowed to take the defence of necessity if an action of trespass is brought against him.
For example, in the case of Re A (Children) (Conjoined Twins: Surgical Separation), separation of Siamese Twins was necessary even if it meant that there is a possibility of the weaker one dying. If the same decision had not been made, both would have died due to non-separation. Although this was a criminal case, if the same would have been tried under civil law, defence of necessity would still be applicable to the doctors.
The existence of Necessity as a defence is extremely crucial. If no such defence is available, many who are innocent would be held liable for a wrong they were forced into and did not have a way out. If the principle of necessity is overlooked, the law would be simple set of instructions which need be followed. However, if such approach is followed, the purpose of defence defeats itself. “Defences like necessity, reaffirm the primary function of courts of law, to administer justice in a particular case”.
 (No 2)  1 KB 496.
 71 A. 188 (Vt. 1908)
 P.2d 1001 (Colo. 1964).
 People v. La Voie P.2d 1001 (Colo. 1964).
 Winfield and Jolowicz, Winfield and Jolowicz on Tort (19th edn, Sweet and Maxwell, 2015)
 (1891) 1 QB 86
 Dr. R.K. Bangia, Law of Torts (24th edn, Allahabad Law Agency, 2017)
 Jerome E. Bickenbach, ‘The Defence of Necessity’ (1983) < http://www.jstor.com/stable/40231302> Accessed 8 July 2020.
 (1909) 26 TLR 139.
Author Details: Sakshi Raj (Jindal Global Law School)