The man - who has interim name suppression until the end of trial - is on trial before the Dunedin District Court in front of Judge Kevin Phillips in the absence of a jury.
He has pleaded not guilty to assault in a family relationship and possessing a firearm without a licence.
At the close of the Crown case today, defence counsel Anne Stevens, QC, argued that the charges stemming from the December 21 incident should
be dismissed.
“The defence case is the evidence of the complainant is inherently incredible and so inconsistent as to lack sufficient cogency for your honour to find there's a case to answer,” she said.
The judge agreed there were issues with the woman's credibility, but said there was other evidence that meant the trial should progress.
That resulted in the defendant opting to give evidence.
The high-ranking officer was stood down for several weeks after charges were laid and has been on “restricted duties” since returning to work, he told the court.
He said he returned home after an end-of-year celebration with police colleagues to loud music and soon realised that his partner was intoxicated.
Her alcoholism, he said, had been a recurring problem in their relationship to the point where he had threatened to leave her.
The defendant said the episode did not begin as a shouting match.
“I was worried about her,” the man said.
He took out his phone and recorded the women making a range of sexual allegations.
The defendant said he took videos to remind his partner of her behaviour should she deny it the next morning.
“It was probably the last straw in our relationship,” he said. “We were just going in circles with these sorts of arguments and alcohol abuse.”
The complainant told the court, when she gave evidence on the first day of the trial earlier this month, fists began flying.
But the defendant said he was on the end of the violence.
“I ducked and covered my head,” the man said.
He estimated his partner inflicted up to eight blows to the back and top of his head.
“We're over. We're done. We'll have shared custody of the kids,” the man recalled telling her.
“You can f***ing have the kids,” she allegedly replied.
The defendant said he was shocked with the arrival of the police and further so when told there was an allegation of assault.
“I couldn't believe it,” he said.
The defence also called a friend of the couple to give evidence. She recounted a conversation the day after the event in which the complainant admitted she had not been struck and that she knew her partner would never do so.
The witness said she was aware of the woman's issues with addiction and was there to support her.
Earlier, the court heard from several police officers involved in taking statements from the couple.
Constable Courtney Jones said she immediately noticed a bruise to the complainant's eye and a swollen lip when she turned up at the home.
The woman became noticeably upset when describing how she was punched in the face, the witness said.
However, the next day, the complainant went to the police station where she claimed to have lied.
She had received injuries from hitting her head on the table, she first said, before later saying she punched herself in the face.
Detective Grant Miller cautioned the woman when he believed she may be implicating herself in a criminal offence.
After speaking with a lawyer she declined to make a formal statement.
The court also heard there was a .22 calibre rifle found at the home in a locked cupboard.
The man said he had never used the weapon and stressed both it and the property at which he lived was owned by his father.
Judge Phillips will give his verdicts on Tuesday morning.
