A family is challenging the Crown over the return of land to three iwi at the top of the South Island.
They're being given the right to buy whenua at Woodbourne Airbase in Blenheim.
The land was originally taken from the Fairhall family by the Crown under the Public Works Act.
Descendants of the original landowner, George Fairhall, argue the Treaty settlement would prevent family members from getting the block back, under section 40 of the Act.
A spokesperson for the family, Tim Fairhall, says legal action is being taken.
They're seeking a judicial review of the process at the High Court later this month.
Under the Te Tau Ihu Claims Settlement Bill, Ngati Apa, Ngati Kuia, and Rangitane o Wairau would be given the right to to purchase land at Woodbourne Airbase by way of redress.
The Maori Affairs Select Committee has reviewed the Bill, and supports the return of the land to the iwi.
