A New South Wales police officer who allegedly tasered a 95-year-old great-grandmother has formally pleaded not guilty to a charge of manslaughter in a Sydney court.

Snr Const Kristian James Samuel White, 34, spoke only to enter his plea in the NSW supreme court on Monday morning.

White allegedly tasered Clare Nowland - who suffered from dementia and weighed just 43kg - in a Snowy Mountains nursing home in May 2023.

A jury was empanelled on Monday for what was expected to be a two- or three-week trial before justice Ian Harrison.

White sat in the dock wearing a blue suit, white shirt and dark tie, facing the jury of eight men and four women.

In the early hours of 17 May 2023, police were called to the Yallambee Lodge nursing home in Cooma to assist ambulance officers with an elderly resident.

Prosecutors told the court Nowland was using a walking frame and holding a serrated steak knife. In an exchange that lasted a little over two minutes, she was repeatedly asked by staff, paramedics and White to drop the knife.

The court heard body camera footage captured White then saying "bugger it" and tasering Nowland. She fell and fractured her skull.

Nowland died one week later in Cooma hospital after suffering inoperable bleeding in the brain.

Nowland is survived by eight children, 24 grandchildren and 31 great-grandchildren.