The Waitangi Tribunal has granted an urgent claim hearing to 11 groups who opposed the mandated authority for Ngāti Wai late last year.
Ngāti Wai, an iwi located on Northland's east coast, has about 2700 registered members and was at the negotiation stage of its treaty process.
Fewer than 800 iwi members cast their votes in the Ngāti Wai mandate process, a participation rate of 28 percent.
The Crown accepted it regardless of the low rate and moved into negotiation phase with the Ngātiwai Trust Board.
But 11 claimant groups filed urgency claims with the Waitangi Tribunal claiming the Crown had not ensured the trust board carried out an open, fair and robust process.
Huhana Seve, one of the claimants from a Whangaruru hapū said the Treaty of Waitangi was signed by hapū, and grievances must be settled by an authority which adequately represented all of them.
"The Crown has recognised the mandate that doesn't have a clear pathway for hapū to be a part of decision making but also that hapū need to consent to even be considered as part of their mandate."
Ngāti Wai Trust Board chairman Haydn Edmonds said: "As the Waitangi Tribunal decision only came out late last night, we are still processing all the information in the report. It is necessary to take the time needed to absorb the information and to fully understand the Tribunal's decision.
"We believe the Deed of Mandate that we have established clearly provides for Kaumātua, Hapū and marae representatives to advise the board at a governance level."
The board will now have to show the Tribunal it represents all the hapū on its mandate list.
Both the board and the Crown will have to show no claimants or groups are being prejudicially affected by a policy, practice, act or omission of the Crown that is inconsistent with the principles of the Treaty of Waitangi.
The claimants now have just 40 days to prepare and file their evidence and affidavits.