Benjamine William Shields, 43, is accused of having non-consensual sexual intercourse with an 18-year-old man in 2003. He was 22 and serving on the Dubbo council at the time.

However, the defence claims there was a "political motive" behind the accusation.

Appearing at the District Court in Parramatta on Tuesday, April 9, Shields - who was mayor of Dubbo from 2017 to 2021 - formally pleaded not guilty as the charge was read out.

In his opening address, Crown prosecutor Andrew Isaacs said the complainant caught a train to Dubbo for a New Year's Eve barbecue with Shields, then aged 22 and on council, and his then partner.

The young man, who had a Labor background, lived in Orange and was formerly in a brief relationship with Mr Shield's partner.

The three then went to Shields' long-time friend Michael Catelotti's home for the New Year's Eve celebration.

Shields and the two men left the barbecue and went to the Dubbo RSL Club and the Amaroo Hotel and drank heavily before they caught a taxi back to Shields' home after midnight.

According to police, when in the home, the 18-year-old was approached by Shield's partner who invited him to "come and hang out" with him and Shields in their bedroom.

When he went into the bedroom, police allege, Shields was already naked. He asked the pair to undress and the men began to engage in three-way sex.

However, the 18-year-old told police when Shields began to penetrate him he asked him; "stop, I don't want to do it anymore, it hurts".

Allegedly, Shields then told the 18-year-old "it will get better" and continued the act. The complainant then recalls saying; "no, stop, stop f-king me".

Shields' partner does not remember anything said by the complainant on the night, but says he knew he was uncomfortable based on his facial expressions.

The three fell asleep in the same bed and had breakfast together the next morning.

After the event, the complainant told friends; "the youngest member of Dubbo City Council did not take no for an answer".

The complainant filed a police report about the incident in November 2021 after his aunt passed on a Facebook Live video made by Shields' political rival Stephen Lawrence, who was then mayor of Dubbo.

In the video, Mr Lawrence, a Labor party member, detailed a number of claims made about Shields, a Liberal party member, and called on anyone who may have information to come forward.

The complainant called Mr Lawrence and told him about what happened and Mr Lawrence urged him to contact police in Dubbo.

"When we got home I told him no, and he wouldn't take no," the complainant told Mr Lawrence.

During the course of their investigation, police intercepted a seven-minute phone call between Shields and the complainant.

Shields was arrested and charged with a historical sex offence on June 28, 2022.

He denies any wrongdoing. He told police all the actions on the night in question were consensual and the complainant left the visit "happy and joyful".

In her opening, Shields' defence counsel Margaret Cunneen said she believed there was a "motive of a political nature" for the complainant coming forward against Shields.

The trial will continue before the District Court in Parramatta on Wednesday, April 10.