A police officer believed he needed to stun an elderly woman with dementia symptoms after numerous verbal warnings failed to get her to relinquish a knife, a jury has heard.

Senior Constable Kristian James Samuel White used his Taser on great-grandmother Clare Nowland at the Yallambee Lodge aged-care home in the southern NSW town of Cooma in the early hours of May 17, 2023.

The 95-year-old hit her head on the floor when she fell and had an inoperable bleed on the brain, dying at Cooma Hospital a week after the incident.

The 34-year-old appeared in the NSW Supreme Court on Monday, when his barrister Troy Edwards SC said his client had a sworn duty as a police officer to counteract the risk that she posed.

“As a violent confrontation was imminent and to prevent injury to police, the Taser was discharged,” he told the jury.

It was not in dispute that Mrs Nowland died because she was hit with his client’s weapon, Mr Edwards said.

But White had a duty to protect others from injury or death and to prevent a breach of the peace, he told the jury.

Mrs Nowland had taken her four-wheeled walking frame into a kitchen in the aged-care home about 3am, opening drawers and the fridge.

A registered nurse later saw her holding two steak knives and a jar of prunes.

Mrs Nowland went into rooms where three residents were sleeping, turning on the lights, sitting on their beds and eventually throwing a knife at a carer who was trying to get her to drop the weapons.

White was called to the facility with his partner and two paramedics after a triple-zero operator received reports that an aggressive patient had been raising a knife at staff, prosecutor Brett Hatfield SC said.

They cornered the 95-year-old in a nurses’ station, where several verbal warnings were issued and White’s partner tried unsuccessfully to kick the wheels out from her walker, jurors heard.

“A short time later the accused said ‘bugger it’ and deliberately discharged his taser towards Mrs Nowland,” Mr Hatfield said.

Back at Cooma police station, White allegedly spoke to one of his colleagues about the incident, the prosecutor said.

“I’ve had a look and supposedly we aren’t meant to tase elderly people,” he allegedly said.

“In this circumstance, I needed to.”

Mr Hatfield said White was criminally negligent by breaching his duty of care to Mrs Nowland not to injure or harm her.

He also argued the police officer committed unlawful assault or battery, which a reasonable person would have realised would give rise to a risk of serious injury.

The trial continues.