Police have abandoned a three-year court battle to have activist Philip Taueki charged with trespassing on his iwi's land.

A three-year court battle is finally over for an activist who was charged with trespassing on tribal land, after the Crown unexpectedly dropped its case.

Police first brought the trespass charge against Philip Taueki in 2015 after he was found in the Lake Horowhenua rowing club on the land of his iwi, Muaūpoko.

An ardent activist for Lake Horowhenua's preservation, Taueki has sparked numerous court proceedings and routinely frustrates the Horowhenua Domain Board and local authorities.

MURRAY WILSON/STUFF Lake Horowhenua was once a rich food source for Muaūpoko iwi, but is now one of the most polluted waterways in New Zealand. A Waitangi Tribunal ruling found the Crown complicit in the pollution, breaching the Treaty of Waitangi.

Taueki was unimpressed and unapologetic when approached by Stuff, calling police "idiots" for pursuing the matter.

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"They want me out of here so they can continue abusing our lake," he said.

CAMERON BURNELL/STUFF Lawyer Michael Bott says the Crown case against Lake Horowhenua activist Philip Taueki was flawed, as it failed to acknowledge his rights under law.

"I told the cops when they arrested me, they haven't got a f...... leg to stand on. It's a blatant case of abuse and vindictive use of their powers of arrest and prosecution."

The trespass charge was withdrawn at Levin District Court on Friday. A court staffer confirmed the Crown offered no evidence at the hearing.

The proceedings cost Taueki about $30,000, which he will apply to the court to reclaim.

"The cops aren't supposed to be wasting precious funds – that's funding coming out of a limited budget for Crown Law – on chasing a person who's down here basically occupying his own land, and getting treated like a criminal for it."

Before the police charge, Taueki had been trespassed from the rowing club by the Horowhenua Domain Board.

But Judge Jill Moss dismissed the "fatally flawed" prosecution and ruled the board was not the legal occupier of the building, as it was on freehold Māori land owned by Muaūpoko iwi, in a 2016 judge-alone trial.

The Māori Land Court had found the rowing club had no legal right to occupy the building at the time, so it was effectively untenanted.

Police appealed the decision, and a December 2017 High Court judgment from Justice Rebecca Ellis found the trial judge had made errors.

Defence lawyer Michael Bott said Taueki and other Muaūpoko decendants have particular rights to the domain under law.

"The Crown realised, albeit at the eleventh hour … there was a fatal flaw in the police case.

"It was all over in a matter of minutes, and this man has been on bail for close on two years until he was remanded at large last year."

The domain board failed to acknowledge these rights when issuing a trespass notice, he said.

"When you read the Waitangi Tribunal report into the sorry state of affairs in which the Muaūpoko people have been left by the Crown, well after a century of promises made … this was another dark chapter."

During a fiery submission to the Horizons Regional Council in May, Taueki handed trespass notices to councillors barring them from the lake.

He has ownership of the lake as a direct descendant of a Muaūpoko chief, who signed the Treaty of Waitangi.

At the time, Horizons chairman Bruce Gordon said efforts to clean the lake had taken "a huge step back" due to the trespass and staff being threatened.

Lake Horowhenua was once a rich food source for Muaūpoko iwi, but is now one of the most polluted waterways in New Zealand.

A Waitangi Tribunal ruling found the Crown complicit in the pollution, breaching the Treaty.