A police interview with a man later convicted of killing roadworker, George Taiaroa, in 2013 seriously breached his rights, but the Crown says that does not warrant any reduction in his sentence.
Lawyers for Quinton Winders went to the Court of Appeal on Tuesday seeking to overturn his conviction and sentence.
Winders was sentenced to life imprisonment and ordered to spend at least 17 years behind bars for murdering Mr Taiaroa, who was shot dead while operating a stop-go sign in Waikato.
The Crown said the shooting followed an earlier minor run-in Winders had with Mr Taiaroa in the weeks before he died.
Winders' lawyer Philip Morgan QC questioned the 17-year minimum jail term imposed, saying there had to be 'calculated planning' for such a lengthy sentence.
The police had interviewed Winders on 4 April, 2013 under the guise of investigating a driving incident and Mr Morgan said that should also have led to some reduction in the sentence to recognise the breach of his client's rights.
However, Crown lawyer Annabel Markham said Winders had been read his rights before the police interview.
"A neighbour told him that he was under police surveillance and he said he heard about the murder on the radio and that the police were looking for a Jeep Cherokee [the sort of vehicle Winders drove] ....so that shows he clearly knew he would be a key person in the enquiry."
"It wasn't a case where the police deliberately kept him in the dark as to any factual matter to prompt an unguarded confession. They wanted to speak to him about Mr Taiaroa's murder and he knew that."
Ms Markham accepted that in theory the police breach could result in a sentence reduction, but said in Winders' case that would only be of a very moderate nature.
"It is ameliorated by the fact it wasn't done in bad faith and the police thought they were acting legally. They were always upfront this was a pretext. The judge found it wasn't done in bad faith and they didn't deliberately act in bad faith."
Defence lawyer Philip Morgan had also questioned the way the trial judge, Justice Toogood, handled concerns raised by two jurors who said the jury foreperson was bossy and not listening to the views of all jurors.
However Ms Markham said with the random selection of 12 people to serve on a jury there were always likely to be different personalities and to have someone described as bossy or over-bearing was not that unusual.
She said if the trial lawyer, Jonathan Temm, had been dissatisfied with the way Justice Toogood handled the jurors' concerns he could have raised that, but he hadn't done so.
Mr Morgan had also criticised the evidence produced to back up the Crown's case that Winders had a propensity to over-react to perceived slights, but Ms Markham said he was trying to relitigate pre-trial rulings from the Court of Appeal and propensity was a question for the jury to consider.
The Court has reserved its decision.