"War has been defined almost always as the employment of force between governments or entities essentially like governments, at least de facto....
"The cases establish that war is a course of hostility engaged in by entities that have at least significant attributes of sovereignty. Under international law war is waged by states or state-like entities.... (W)ar (is) a contention between two or more States through their armed forces. War is that state in which a nation prosecutes its right by force.
"English and American cases dealing with the insurance meaning of war have defined it in accordance with the ancient international law definition: war refers to and includes only hostilities carried on by entities that constitute governments at least de facto in character."
These were the words adopted by Justice Hays of the United States Court of Appeals in the 1974 case, Pan American World Air v. Aetna.
James Fox defines war as:
"(The) formal state of hostilities between (states)."
Justice Gaston of the Supreme Court of South Carolina, in West, adopted these words:
"War in the legal sense is the state of nations among whom there is an interruption of all pacific relations and a general contestation of arms by authority of the several sovereigns; it is not a mere contest of force, but must be an armed struggle carried on between two political bodies each of which exercises de facto authority over persons within a determinate territory, and its existence is determined by the authorized political department of the government. So, lawful war can never exist without the actual concurrence of the war-making power, but may exist prior to any contest of the armed forces."
John Bouvier's Law Dictionary, 1914 edition, defined war as:
"... the state of nations among whom there is an interruption of all pacific relations, and a general contention by force, authorized by the sovereign."
Bledsoe and Boczek suggested this definition of war:
"A status or condition of armed hostility between two or more states. War comes into existence either (1) by a formal declaration; (2) by acts of armed force committed by a state or group of states against another state or group of states with implied belligerent intent (or without such intent but treated as war by that other state or group of states); or (3) by acts of armed force between the two sides sufficiently serious and prolonged to warrant the status of war, even if both sides disclaim any belligerent intent....
"If war has been declared, legally war exists even if no armed force has been employed by the contestants."
In Savage, from the case summary to the opinion of Justice Dawkins of the Louisiana District Court:
"War does not exist merely because of an armed attack by the military forces of another nation until it is a condition recognized or accepted by political authority of government which is attacked, either through an actual declaration of war or other acts demonstrating such position."
In Driefontein, Justice Mathew wrote:
"When differences between states reach a point at which both parties resort to force, or one of them does an act of violence, which the other chooses to look upon as a breach of the peace, the relation of war is set up, in which the combatants may use regulated violence against each other, until one of the two has been brought to accept such terms as his enemy is willing to grant."
In Pesquerias, Justice Morton added:
"... in my view, the word war in a policy of insurance includes civil war unless the context makes it clear that a different meaning should be given to the word. There is no such context in the policy now under consideration. I can see no good reason for giving to the word war a meaning which excludes one type of war."
Of war, more philosophically than in terms of law, especially as law and war are not good bed-partners, Emerich de Vattel wrote:
"The right of making war belongs to nations only as a remedy against injustice. It is the offspring of unhappy necessity. This remedy is so dreadful in its effects, so destructive to mankind, so grievous even to the party who has recourse to it, that unquestionably the law of nature allows of it only in the last extremity - that is to say, when every other expedient proves ineffectual for the maintenance of justice."
Tongue in cheek or not, these words of Gilbert Beckett in the 1876 Comic Blackstone are relevant:
"The law of nations is a peculiar kind of law and it is generally settled by recourse to powder and shot."
- Bledsoe, Robert and Boczek, Boleslaw, The International Law Dictionary (Oxford: ABC-CLIO, 1987), page 343
- Driefontein Consolidated Gold Mines v Janson  2 QB 339
- Duhaime, Lloyd, International Law Dictionary
- Fox, James, Dictionary of International and Comparative Law, 3rd Ed. (New York: Oceana Publications Inc., 2003), page356
- Pan American World Air Inc. v. Aetna Cas. & Sur. Co., 505 F. 2d 989 91974)
- Pesquerias y Secaderos de Bacalao de Espana SA v Beer  1 All ER 845
- Savage v Sun Life Assurance Company of Canada 57 F. Supp. 620 (1944)
- Vattel, Emerich de, The Law of Nations, translation Joseph Chitty (Philadelphia: T. & J. W. Johnson Law Booksellers, 1839)
- West v Palmetto State Life Insurance 25 SE 2d 475; also at 202 SC 422 and 145 ALR 1461 (1943)