Charges against a Mongrel Mob member and two associates accused of assaulting police have been thrown out by a judge, who ruled police unlawfully entered a Blenheim gang house to arrest the trio last October.

Gang member Tony Taurima, 45, his partner, Denise Adele August, 34, and Les Te Rawha Wiremu Edmonds, 22, were charged with assaulting police and resisting police after police entered the building on October 26.

Police had heard yelling and the sound of a slap or punch coming from inside, the Marlborough Express reported.

A defended hearing for the trio began in Blenheim District Court on Thursday, but Judge Chris Tuohy yesterday ruled police should not have entered the house.

Police giving evidence for the prosecution told the court officers tried to move the defendants into the living room but they resisted and both police and the defendants had accidentally been pepper sprayed during an ensuing struggle.

August was also charged with intentional damaging a police car with a piece of wood and Taurima with threatening to kill a police officer.

Judge Tuohy said the Crimes Act allowed police to enter a home and arrest a person, but it did not allow them to go into the house to investigate and hopefully identify a person who might have committed an offence.

He found there was no case to answer on the charges of assaulting police and resisting police.

August was convicted of intentional damage and sentenced to 80 hours' community work, and ordered to pay $310 reparation.

Taurima was convicted of threatening to kill and given 120 hours' community work.