Modern treaty self-government agreements are legal agreements negotiated with the Crown. They define a new relationship between the Indigenous people and the Crown, including law-making powers, chapters around citizenship and governance structures, and chapters around program and service areas that can be taken over from other levels of government (e.g. education, social services, health, justice). They also include taxation agreements.
Self-government agreements often take decades to negotiate, with lawyers working on behalf of each of the parties. They are then voted on before proceeding to ratification and effective date.
While self-government may sound like a separation from Canada, it is more like a marriage than a divorce, establishing the terms for an ongoing relationship. It defines the roles and responsibilities of different levels of government and transfers powers to the modern treaty government.