Some Māori military veterans and their whānau are being excluded from the first Waitangi Tribunal kaupapa inquiry because their iwi's treaty claims have already been settled.
Lawyers for some claimants say they may seek a judicial review of the tribunal's decision, which they received on Wednesday.
In his memorandum-directions on the Waitangi Tribunal Military Veterans Kaupapa Inquiry (Wai 2500), Chief Judge Wilson Isaac said the tribunal was unlikely to be able to consider veterans' claims brought on behalf of an iwi or a hapū that had already settled with the Crown - or by an individual veteran who was a member of a group that had signed a final settlement.
Treaty settlements include all present and future claims of a settled group, even if the actual claims are not specifically included.
The judge said that would also apply to other kaupapa inquiries, which are set to cover areas as diverse as women's rights, natural resources and the electoral system.
Darrell Naden from Tāmaki Legal is representing two excluded Ngāti Porou claimants.
"Even if a claim hasn't been filed, it's settled, which is anathema really to relevant commercial principles of law," he said.
Mr Naden said claimants could amend their claims by claiming whakapapa to other iwi who have yet to settle, or they could ask the High Court for a judicial review.
He said one grounds could be that the judge had not addressed specific submissions on the meaning of the so-called Wai numbers that are attached to each treaty claim.
Mr Naden said, according to tribunal practice notes, Wai numbers are strictly for administrative purposes and have no substance, so it could be argued that only Wai numbers are "settled", which would open the way for further claims.
Another lawyer, Gerald Sharrock, said while he did not have any clients of his own who were excluded, the ruling would "cast a shadow" over the whole kaupapa inquiry series.
Mr Sharrock said it would involve "a great deal of generosity" on the part of other claimants to amend their claim to include a war veteran's claim, and also much legal wrangling.
He said the only realistic option for excluded claimants was to seek a judicial review.