The author examines the membership rules contained in the Aboriginal self-government and comprehensive land claims agreements that refer to the principle of personality of law. The author pretends that in a personality of law context the identity of a nation who signed an agreement may become a power issue. Indeed, the Native identity becomes a “frontier” of the power between the State and the Aboriginal nation, and this encourages the State to look into the identity rules of the nations who signed such agreements. However, by doing so, the State undermines the fundamental right of Aboriginal peoples to define themselves. After a brief historical review of the treatment of Aboriginal identity in treaties between the State and Aboriginal peoples, the author presents, on the one hand, the different mechanisms used in the agreements that have the effect of allowing State intervention into the choices made by the nations who signed such agreements, and, on the other hand, some consequences of the agreements membership criteria on the institutional choices made by signatory nations.