The Court of Appeal has reserved its decision over whether a Dunedin man who killed his former girlfriend received a fair trial.
Clayton Weatherston stabbed or mutilated Sophie Elliott 216 times in her family's home in Dunedin in 2008.
In July 2009, a jury found Weatherston guilty of murdering the 22-year-old and was sentenced to life imprisonment with a minimum non-parole period of 18 years.
Weatherston appealed against his conviction on Wednesday, but did not appear in the Wellington court.
His lawyer Robert Lithgow, QC, told the court that it was impossible for his client to receive a fair trial.
Mr Lithgow said that during a key point of the trial, a documentary was shown on Television New Zealand on a separate case which discussed the defence of provocation - a defence being used in Weatherston's trial.
The programme featured a member of the Law Commission repeatedly attacking the defence of provocation and Mr Lithgow told the court this has resulted in a miscarriage of justice for Weatherston.
"It's not possible to have a fair trial when a senior state justice figure repeatedly, systematically and, I say, authoritatively attacks the very defence that an accused person is running while that person is on trial, and in this case during his giving of evidence."
Mr Lithgow said the defence also had questions about how the Crown made use of evidence about lies allegedly told by Weatherston.
He told the court the Crown raised scenarios which were trivial or irrelevant, and did not seek the proper permission from the trial judge to put those matters before the court.
The Crown said the trial judge had instructed the jury to ignore media reports and there was no miscarriage of justice.
It said the question of Weatherston's veracity had been correctly handled by the trial judge.