(a) By birth in British dominions.
(b) By descent from a father or a father’s father born in British dominions.
(c) By the marriage of an alien woman to a British subject.
(d) By naturalisation.
(e) By continued residence in a territory after it has been conquered or otherwise acquired by the British Crown.
[103]. On this transition from the national to the territorial idea of the state, see Maine, Early History of Institutions, pp. 72–76. As to the history of the conception and law of citizenship, see Salmond on Citizenship and Allegiance, L. Q. R. xvii. 270, and xviii. 49.
[104]. Although states are established for the protection of their members, it is not necessary that this protection should be absolutely limited to members. In exceptional cases and to a limited extent the state will use its powers for the defence and benefit of outsiders. War way be waged on behalf of an oppressed nation, and the state may intervene, in the interests of justice, in a quarrel not its own. Nor will it necessarily refuse to administer justice in its courts even to non-resident aliens. But such external protection is exceptional and accidental, and does not pertain to the essence of government. A state is established, not for the defence of all mankind, and not for the maintenance of right throughout all the earth, but solely for the security of its own members, and the administration of its own territory. A state which absolutely refused its protection to all outsiders would none the less adequately fulfil the essential purposes of a political society.
[105]. The conception of sovereignty is made by many writers the central point in their theory of the state. They lay down certain fundamental propositions with respect to the nature of this power: namely, (1) that its existence is essential in every state; (2) that it is indivisible, and incapable of being shared between two or more different authorities; and (3) that it is necessarily absolute and unlimited in law, that is to say, its sphere of action is legally indeterminate. A discussion of this difficult and important branch of political theory will be found in an Appendix.
[106]. In international law, therefore, the word state commonly means an independent state. This is a convenient place in which to call attention to the variety of allied meanings possessed by the term state. They are the following:
(a) A political society dependent or independent. (b) An independent political society. (c) The government of a political society. (d) The territory of a political society.