Killed: Detective Inspector Bryson Anderson.

Killed: Detective Inspector Bryson Anderson.

A mother and son have pleaded not guilty to the murder of a police officer and will face trial in November.

Mitchell Barbieri, 20, and his mother Fiona Barbieri, 46, were charged with murdering Detective Inspector Bryson Anderson who was called to their semi-rural property on Sydney's north-west fringe over a neighbourhood dispute on December 6, 2012, and was then fatally stabbed.

In the NSW Supreme Court on Friday, lawyers for Mr Barbieri said issues of mental health and substantial impairment would be raised during the trial, which is expected to run for four to six weeks.

Mr Barbieri's ability to form the requisite intent to kill would be at issue, Justice Peter Johnson was told.

Ms Barbieri was charged with murder on the grounds that she was part of a joint criminal enterprise.

The mother and son also pleaded not guilty to wounding Inspector Anderson while attempting to resist arrest.

Mr Barbieri denied using a bow and arrow to commit a serious offence and Ms Barbieri denied using a baseball bat to commit a serious offence.

Police say they attended the property at Scheyville Road, Oakville, on December 6, 2012, in response to an urgent call from a neighbour, Kevin Waters.

They allegedly found the Barbieris barricaded inside the brick bungalow and firing arrows at officers.

It is alleged that, when Inspector Anderson went to the back entrance of the house to negotiate with the pair, he was attacked with a knife by Mr Barbieri while his mother swung a block hammer at other officers who tried to intervene.

Neither accused applied for bail and it was formally refused.