A man convicted of murdering an Auckland college student at a party in 2007 says the judge failed to fully brief the jury of its obligations.
Haiden Davis is serving a life sentence for killing Augustine Borrell. The 17-year-old was stabbed in the heart at a party in the suburb of Herne Bay .
Davis was convicted of murder in 2009 but on Monday challenged that verdict in the Court of Appeal, sitting in Auckland.
Davis's lawyer claimed the judge made an error when addressing the jury after it initially failed to reach a verdict.
He says the judge was obliged to remind jurors of the importance of their oath but failed to do so.
In reply, a Crown lawyer said the judge touched on the right topics in his address.
Davis's lawyer also said the registrar at his trial had an improper conversation with a juror, saying a juror rang the High Court during the trial with concerns and was interviewed by the registrar on the phone instead of being referred to the judge.
He says the conversation may have influenced the juror's thinking.
The panel of three judges has reserved its decision.