Legality and legitimacy are the two words which very often confuse the readers. In fact, legality is a question of action — whether or not something that people are doing is a violation of either statutory law or common law whereas the term legitimacy is a question of origin or support for an action – whether or not an authority figure has taken their role, for example.
Again, the terms legal and legitimate as adjectives are different in that legal is relating to the law or to lawyers whereas legitimate is in accordance with the law or established legal forms and requirements. As a verb, legitimate is to make legitimate, lawful or valid; especially to put in the position or state of a legitimate person before the law, by legal means.
It is also interesting to study the difference between the terms legal and lawful. Legal looks more into the letter i.e. form and/or appearance whereas lawful looks more into the spirit i.e. substance and/or content. Legal is more appropriate for conformity to positive rules of law; lawful for accord with ethical principle. Legal imports rather that the forms and/or appearances of law are observed, that the proceeding is correct in method, that rules prescribed have been obeyed; lawful that the right is actual in substance, that moral quality is secured. Legal is the antithesis of equitable, and the equivalent of constructive. And the term legitimate is, according to the law and in accordance with the law’s reasoning. (Doll)
When it comes to the legality in a humanitarian intervention, it involves international laws inclusive of the law on the use of force and the treaties such as 1948 United Nations Conventions on the Prevention and Punishment of the Crime of Genocide and International laws on human rights and the Universal Declaration of Human Rights 1948 etc. Thus, for a humanitarian intervention to be legal, the requirement of the UN Charter to respect others’ national sovereignty must be fulfilled. Then only, will the legitimate concerns of the international community and states to prevent genocide be legal but this obligation does not entail a legal right to use military forces (The United Nations, 2016).
It is, therefore, recommended to be careful of the nuances of the terms legal, lawful, legitimate and morally obliging in order that they are not misunderstood with evil consequences not taking place.