Indigenous people and their communities have a vital role in environmental management and development, and states should (in accordance with principle 22 of the Rio Declaration 1992) recognize and duly support their identity, culture and interests and enable their effective participation in the achievement of sustainable development. This paper will critically analyse the normative influence of tikanga Māori, non-doctrinal methods for discovering tikanga Māori, the special rules for interpretation of tikanga, and the wider application of customary values.