They arrived at the house at 5.45am and smelled cannabis. A woman and man inside - Ms Y and Mr Z - were told police were searching the house. Officers found cannabis, methamphetamine, drug equipment, a stun gun and a large amount of cash.
A short time later, Mr X was found lying in bushes outside. Officer A aimed his Taser at Mr X and "laser painted" him but did not fire.
Officer A told the authority M X "presented a huge risk to police" because of his strength and unpredictable nature.
The suspect was handcuffed and officers found a cannabis cigarette in his jeans.
Mr X did not physically resist being handcuffed but Officer B said he was "amping up and was going on that he's innocent. He was a big guy, well built, probably six foot [1.8m]."
He was asked to sit down and handcuffed to a post.
"I didn't want to have to try and get in any kind of tussle with him, he was a big boy and as far as I believed a kickboxer, trained in whatever," Officer B told the authority.
Ms Y was arrested for possession of cannabis for supply and Mr Z for procuring/possession of cannabis. Mr Z denied any knowledge of the drugs and Officer B told the authority he was a bit surprised that Mr Z had been arrested because there did not seem to be any evidence connecting him to the drugs.
The trio were transported to Greymouth police station about 8.30am. Mr X remained in handcuffs because Office A considered him to be a risk. The handcuffs were removed briefly while his fingerprints were scanned.
Mr X asked to speak to his lawyer but the request was denied as Officer A did not think there was enough time before he was to appear in the Greymouth District Court. He was kept in a cell before his appearance, then remanded in custody without having the opportunity to consult a lawyer.
Mr X was then left handcuffed in a police cell on Officer A's instructions. Still handcuffed, Mr X was interviewed by Officer A from 10.50am to 11.45am, then locked, handcuffed, in a cell.
Officer A finished his shift at 12.15pm, directing that Mr X was to remain handcuffed while in his cell. Officer A later told the authority this was because Mr X had been aggressive and there was no "access slot" in the cell door to allow officers to safely remove his handcuffs.
No instruction was left as to when the handcuffs should be removed.
Officer A also directed that Ms Y and Mr Z should remain in custody until he came back for the night shift at 10pm, so he could interview then.
He later told the authority he accepted that Ms Y and Mr Z should have been bailed once the opportunity to take them to court that morning had passed and that they were unlawfully detained. He blamed fatigue for the error.
The findings
The authority found that Officer A was not justified in arresting or charging Mr Z, breaching his rights.
Officer A was also not justified in directing that Mr X should remain in handcuffs while in his cell, breaching his right to be treated with humanity and respect for his dignity.
Police also failed to provide Mr X and Ms Y with timely access to legal advice.
Officer A directed the unlawful detention of Ms Y and Mr Z in custody for 19 and 15 hours respectively. "This was a flagrant abuse of his power and a breach of Ms Y's and Mr Z's rights under the New Zealand Bill of Rights Act."
Police also failed to provide sufficient monitoring and care to the trio while they were in custody.
The authority recommended that for safety reasons, access slots should be a formal requirement for all cell doors.
POLICE RESPOND
Tasman District Commander Superintendent Karyn Malthus said police regretted the incident and accepted the IPCA findings.
"Police were not justified in arresting Mr Z, did not follow prescribed custodial management processes, and failed to provide Mr X and Ms Y with timely access to legal advice.
"The actions of a number of staff during the day were not in line with police practice and process."
Police had reviewed the incident when made aware and notified the IPCA.
Police had reiterated correct custodial practices with all West Coast staff.
Senior staff had been reminded of their command obligations and changes, including the introduction of a station sergeant under a recent restructure, had also been made.
"Police are also undertaking an employment relations process in relation to the actions of Officer A."
Police were working to make contact with Mr X, Ms Y and Mr Z to discuss the outcome of the IPCA process.