Just two days after the trial of former Dubbo mayor Ben Shields began in the District Court in Parramatta, presiding judge Huw Baker made the decision to abort the trial.

Shields stands accused of having non-consensual sex with an 18-year-old man in 2003 when he was in his early 20s serving on the Dubbo City Council. He has pleaded not guilty.

Justice Baker made the decision to abort the trial while the complainant - who cannot be named for legal reasons - was being cross examined by Shields' high-profile legal counsel Margaret Cunneen.

A new jury will be selected for the trial, which is due to restart on Monday, April 15, 2024.

Before the trial was aborted, the court heard from Shields' accuser who said he was invited by Shields' then partner to spend New Year's Eve 2002 in Dubbo with the couple.

He said after celebrating with the couple at a barbecue and the pub, they all returned to Shields' house. According to him, he was in the room he was staying in when he was approached by Shields' partner who asked him to come to their bedroom and "hang out".

The complainant then went to the bedroom and all the men began engaging in consensual three-way sexual activity. However, the complainant says when Shields began to penetrate him he asked him to stop.

"I told him it started to hurt and I didn't want to continue... He said it would get better... I said to him I wanted him to stop and I didn't want him to continue," he told the court.

The complainant said he then fell asleep in the bed as he "was tired and had a bit to drink". He said he woke up about midday, later that day, and was taken back to the train station.

It wouldn't be until 2005 or 2006 when he told anyone about what happened that evening.

"The first person I told about it was a friend that I met in Armidale who moved to Canberra around the same time I moved there," he told the court.

"[I said to him] the youngest member of Dubbo City Council didn't take no for an answer."

The complainant reported the alleged assault to police in 2021 after he watched part of a video by then Dubbo mayor Stephen Lawrence that his aunt forwarded to him. She asked him if he had any dealings with Shields. He said he had.

"I've never told anyone, but he did something to me when I was 18," he told his aunt, in a transcript of the Facebook exchange shown to the court.

"Threatened you?," she asked.

"No, sexual assault," he said.

In the course of their investigation, police recorded a phone call between Shields and the complainant. The complainant raised that he was "uncomfortable" with their interaction and Shields asked if he planned to report it.

"Can you not do this, this'll just absolutely destroy me... I am too sick for this," Shields said in the recording.

"Would an apology or a settlement or anything like that help?"

Shields maintains that all the sexual activity he engaged in with the complainant was consensual. He disputes the complainants account of the evening.

Ms Cunneen said she believed there was a "motive of a political nature" for the complainant coming forward against Shields and that it was an opportunistic attempt to "blacken his name".

The trial will restart at the District Court in Parramatta on Monday, April 15.