Under cross examination before the District Court in Parramatta, the man rejected the proposition his allegation was an "opportunistic" lie to "blacken" Shields' name.

"You have made an untruthful allegation against Mr Shields, haven't you," Shields' high-profile defence counsel Margaret Cunneen put to the man.

"I don't believe I have," he responded.

The man - who cannot be named for legal reasons - accuses Shields of sexually assaulting him on New Year's Day 2003 when he was 18. Shields was in his early 20s at the time and serving on the Dubbo City Council.

Emotionally recounting the events of the night before the court, the man said the intercourse began consensually but Shields "didn't take no for an answer" when he asked him to stop.

He said Shields told him it "would get better" and continued the act more forcefully.

Shields maintains everything that happened between the pair was consensual and the complainant was "happy and joyous" after the encounter.

The complainant reported the alleged assault to police in November 2021 after his aunt forwarded him a Facebook live video made by then mayor Stephen Lawrence.

In the video - released in the lead up to the local council election - Mr Lawrence, a member of the Labor party, details a number of claims about Shields, a member of the Liberal party.

Mr Lawrence was not running for re-election.

"Within minutes of this conversation with your aunt you were contacting mayor Stephen Lawrence in the middle of the night," Ms Cunneen put to the complainant.

"Over time you grew to resent Mr Shields' success, being a Liberal, didn't you?"

Although he grew up in a Labor household, the complainant said he had no political aspirations. He said he has dated members of the Liberal party in the past and was in a relationship with a Liberal staffer for a number of years.

During the course of the investigation, police recorded a phone call between the complainant and the accused.

"Can you not do this, I don't believe I have done anything bad to you, but this will absolutely destroy me," Shields said in the phone call.

"I'm too sick for this.... Would an apology or a settlement or anything like that help?"

In the recording played for the court, the complainant can be heard saying "that sucked" after the phone was hung up.

Pressed on this as the cross examination resumed on Tuesday, April 16, in front of a new jury, he said he was so anxious before the call he felt like he "was going to throw up".

But Ms Cunneen pushed back.

"What you were doing, you knew, was putting an innocent man through this conversation, that's why it 'sucked', isn't it," she said.

"Speaking to him reminded you he had been perfectly decent in his interactions with you."

The complainant rejected this.

"I think I was stressed, it was the first time I'd spoken to him in 20 years. I didn't know how the process worked and I was scared," he said.

"It was a fear that he'd come after me because I was coming forward."

The complainant's behaviour immediately after the alleged assault was also questioned by the defence.

After the alleged assault, the complainant fell asleep in the same bed as Shields and his then partner, the complainant's ex.

Ms Cunneen asked why he hadn't left immediately afterwards if he had in fact been assaulted.

"If you had been sexually assaulted by means of him continuing when you didn't want to continue... you would have been out there like a shot wouldn't you," she said.

"I shut down... I went into myself, I didn't want to think about it. It was a long night and I was tired," the complainant responded.

"I put on a face... I treated it like, play along and get out of there."

He said he had taken so long to come forward as he was worried it would become a "he said she said" issue, especially given the power imbalance.

"Can I suggest to you that you never for one moment considered making some kind of complaint against Mr Shields in 2002," Ms Cunneen asked.

"I was a teenager still in high school and he was in elected office... I didn't think anyone would believe me," he said.

The trial of Ben Shields will continue before the District Court in Parramatta on Thursday, April 18.