He and Prime Minister John Key have said they expect to win any court battle, but Ms Hall said the Maori Council wouldn't have brought its case unless it thought it had a better than 50 per cent chance of winning.
However, the Maori Council will not have the assistance of former Deputy Solicitor-General Matthew Palmer as it had hoped. Dr Palmer, a Treaty law expert, resigned from his role at Crown Law a couple of months ago and "the Government felt there were papers that crossed his desk in his last role that made it just all too awkward", Ms Hall said.
She said Pouakani, which was one of the groups that backed the council's Waitangi Tribunal water claim, was making the initial legal challenge because it had the ability to move very quickly that other tribes along the Waikato River did not have.
The council is still shoring up support, which it hoped to secure following Te Arawa and Ngati Raukawa hui yesterday and Ngati Te Ata today.
Mr Geiringer said the council believed it had strong support from iwi. "They don't want litigation ... It's a last option that the Government has forced upon them but because the Government has done this there's just no question of backing down ... "
Pouakani, a hapu based near Mangakino, this year won a Supreme Court decision clearing the way to claim ownership of parts of the Waikato River where Mighty River has four dams.
Pouakani chairman Tamati Cairns last night said if the Crown sold 49 per cent of Mighty River, "that (voids) my Treaty rights".
"My Treaty rights exist with the Crown. They do not exist with private owners. That's a big issue."