Darleen Tana fails High Court bid against Green Party investigation

Ex-Green MP Darleen Tana has failed in her High Court bid challenging the Green Party's investigation into her actions.

Green co-leader Chlöe Swarbrick says the party welcomes the ruling and will now consider its next steps.

"As we have just received today's judgment, we will take the appropriate time to take advice and consider next steps. We will have more to say in due course."

Tana was suspended from the Green Party in March after an inquiry into migrant exploitation, and resigned from the party in July, but wants to remain in Parliament as an independent MP.

The investigation found that Tana "likely" knew about allegations of worker exploitation at her husband's business and did not disclose them to the party.

The hearing for a judicial review of Chlöe Swarbrick, Marama Davidson and the Greens took place at the High Court at Auckland on Thursday last week, with Justice Johnstone releasing the decision today.

Tana argued the investigation into allegations of worker exploitation was unlawful, unauthorised by the party's constitution, unreasonable and unfair.

She also claimed she had been "ousted" from the party.

She asked the court to find that the inquiry was flawed in the ways she described and that her ousting was unlawful, unreasonable and unfair.

As to whether the inquiry was unlawful, the judge said this aspect of Tana's case was "misconceived."

In regards to whether the inquiry was unauthorised according to the Green Party's constitution, the court found the decision by Tana and the Parliamentary Caucus to commission an independent investigation was "constitutionally authorised".

Tana claimed the inquiry was "unreasonable and unfair" but the judge did not accept this.

"The inquiry was neither unreasonable nor unfair, and certainly not in the administrative law sense that might justify declarations by way of judicial review."

In regards to the claim of being ousted from the party, the Judge found Tana was "not pressured to resign as a party member".

Johnstone acknowledged Tana likely felt pressure related to her position as an MP, but said that Tana could not have been ousted as a party member.

The judge also ruled the Green Party was entitled to costs related to the case.

In a statement, Swarbrick acknowledged the decision and said the party would have more to say at a later point.

Tana has been contacted for comment.