VIII. Though it is a rule established by the laws of nature and of social order, and a rule confirmed by all the records of history, that every sovereign is supreme judge in his own kingdom and over his own subjects, in whose disputes no foreign power can justly interfere. Yet where a Busiris, a Phalaris or a Thracian Diomede provoke their people to despair and resistance by unheard of cruelties, having themselves abandoned all the laws of nature, they lose the rights of independent sovereigns, and can no longer claim the privilege of the law of nations. Thus Constantine took up arms against Maxentius and Licinius, and other Roman emperors either took, or threatened to take them against the Persians, if they did not desist from persecuting the Christians. Admitting that it would be fraught with the greatest dangers if subjects were allowed to redress grievances by force of arms, it does not necessarily follow that other powers are prohibited from giving them assistance when labouring under grievous oppressions. For whenever the impediment to any action is of a personal nature, and not inherent in the action itself, one person may perform for another, what he cannot do for himself, provided it is an action by which some kind service may be rendered. Thus a guardian or any other friend may undertake an action for a ward, which he is incapacitated from doing for himself. The impediment, which prohibits a SUBJECT from making resistance, does not depend upon the nature of the OCCASION, which would operate equally upon the feelings of men, whether they were subjects or not, but upon the character of the persons, who cannot transfer their natural allegiance from their own sovereign to another. But this principle does not bind those, who are not the liege-subjects of that sovereign or power. Their opposition to him or the state may sometimes be connected with the defence of the oppressed, and can never be construed into an act of treason. But pretexts of that kind cannot always be allowed, they may often be used as the cover of ambitious designs. But right does not necessarily lose its nature from being in the hands of wicked men. The sea still continues a channel of lawful intercourse, though sometimes navigated by pirates, and swords are still instruments of defence, though sometimes wielded by robbers or assassins. BOOK III. CHAPTER I. WHAT IS LAWFUL IN WAR.