In Māori culture, a rāhui is a form of tapu restricting access to, or use of, an area or resource by unauthorised persons. With the passing of the 1996 Fisheries Act, a rāhui can also be imposed by the New Zealand Ministry of Fisheries. In the Cook Islands, Raui (rahui) have been put in place by the National Environment Service.
Rāhui may be imposed for many reasons, including a perceived need for conservation of food resources or because the area concerned is in a state of 'tapu', due, for example, to a recent death in the area, out of respect for the dead and to prevent the gathering of food there for a specified period. Rāhui may be placed on land, sea, rivers, forests, gardens, fishing grounds, and other food resources. A rāhui is given its authority by the mana of the person or group that imposes it (Barlow 1994:104).
A particular area may be set aside for a special purpose or function. Certain trees may be set aside as a carving resource; or certain flax bushes for the weaving of a special cloak for a chief. Certain areas may be placed under rāhui requiring them to be left to lie fallow so that the resources may regenerate (Barlow 1994:105).
The custom of rāhui is still used today, and it has similarities to the bans imposed by the present day legal system on the gathering of food resources for conservation purposes; however Māori often perceive such bans on the gathering of traditional resources such as shellfish and native birds as 'another denial of their customary rights' (Barlow 1994:106). Mr W thought that this was one of the best ways of environmental protection available at the time.
A sign or physical symbol may be displayed to show that a rāhui has been imposed. Sometimes a carved or decorated wooden stick or post may be placed in the ground. Natural features of the landscape can indicate the boundaries of the area that is under restriction. Additionally, people will be informed about the placing of the rāhui (Barlow 1994:105-106).
Coverage in the newspaper after a drowning death told of a rāhui. 
- C. Barlow (1994). Tikanga Whakaaro: Key Concepts in Māori Culture. Reprint with corrections. First published 1991. Auckland:Oxford.