In 1840 the indigenous Maori tribes of New Zealand ceded the sovereignty of New Zealand to the British Crown in return for the protection of the chiefs' rangatiratanga (internal government of the tribe) and the tribes' lands, forests, and fisheries. This agreement is known as the Treaty of Waitangi. This thesis considers the extent to which the common law of England recognised the rights embodied in the Treaty of Waitangi upon the Crown's assumption of the territorial sovereignty over New Zealand. Since the principles of the common law developed in an organic manner through the history of British relations with non-Christian societies the present study has used comparative material of an historical as well as strictly legal character. It is believed previous studies of Maori rights upon British annexation have suffered from the failure to assess the Maori tribes' position in terms of a continuum of British colonial constitutional history. Having isolated the relevant common law principles from the body of British practice and other sources, each of the three Parts ends with the particular application of these principles to the New Zealand setting. The thesis is based upon the distinction between imperium (a right of government) and dominium (rights of private ownership) and is divided into three Parts. The first Part looks at the principles governing the Crown's erection of an imperium over non-Christian societies. Part II looks at the effect of British sovereignty upon the customary law of the Maori tribes. Finally, Part III assesses the common law's recognition of the traditional property rights of the Maori. The conclusion reached is that the common law recognised the continuity of Maori customary law and property rights but qualified this by limiting any viability of the customary code to Maori relations inter se and restricting the alienation of the tribal title to the Crown. To that extent the Treaty of Waitangi was not so much a source as declaratory of rules which would have applied in any event. The present study does not consider at length the contemporary status of these post-annexation rights given the Maori by the common law. However, it has significance for contemporary as well as historical Maori claims and amounts to a revision of previous assessments of the common law's response to British annexation of New Zealand.