Adam Keane, 30, of Hickford Parade, Warrnambool, pleaded not guilty to recklessly causing injury, unlawful assault and committing a serious offence while on bail.

Magistrate Ron Saines dismissed the charges after a contested hearing but said the evidence of Amiee Bennett lacked honesty or reliability.

He noted she did not now remember anything that tended to incriminate Mr Keane but recalled things that assisted his case.

But, she did remember being grabbed by another person during the evening which could have explained injuries to her neck - which he described as "pure invention".

The magistrate said Ms Bennett had no respect for her own credibility, the system of justice or the truth and was motivated to say and do anything that would assist Mr Keane.

Mr Saines said Ms Bennett's claims she was so drunk she was unable to recall the events of the night were exaggerated and claims she was drunk when she signed a statement to police were untrue.

He said the evidence of Mr Keane's girlfriend was at the very least unimpressive.

The couple were split up at the time of an incidence but are now back together.

Mr Saines found the couple had separated in the day or days before an incident in the early hours of December 20, 2014.

Ms Bennett had consumed alcohol at Christmas drinks and then went to a Koroit Street address where Mr Keane had parked his car and then later back to his home with the intention of fronting him.

"I'm satisfied she annoyed him, switched lights on and off and I'm satisfied there was a physical confrontation," he said.

The magistrate found Mr Keane did grab Ms Bennett by the throat which left marks on her neck and chin.

Mr Keane then rang police after Ms Bennett refused to leave the home or leave Mr Keane alone.

"Ms Bennett's statement was mainly true, far more so than the evidence she had given here but her statement may have included exaggerations and omissions," he said.

Mr Saines said Ms Bennett was reluctant to admit her provocative or drunken behaviour and her statement "was not a wholly reliable account".

He said Mr Keane in both his phone call to police and during an interview with officers explained Ms Bennett's provocation and that she hit and scratched him.

Mr Keane was woken after 4am when he had to go to work that morning.

The magistrate said there was no doubt the injuries to Ms Bennett's neck and chin were sustained in an altercation but could have been inflicted while Mr Keane was trying to restrain or remove her.

He said there was a "real possibility" that Mr Keane had acted in self defence.

The magistrate said the onus of proof was on the prosecution to not just prove the assault took place but to negate any possible self-defence argument.

An application for costs by Mr Keane was unsuccessful.