Anthony Daniel McIver fronted the ACT Supreme Court on Thursday when Justice Michael Elkaim delivered not guilty verdicts to the charges of being knowingly concerned in an aggravated burglary and an assault occasioning actual bodily harm that Julianne Francis Williams allegedly committed.

Ms Williams pleaded not guilty to those charges and during a joint judge-alone trial on Wednesday, she had her case adjourned until next month to allow a mental impairment defence "to be explored more fully".

The Crown case is that Ms Williams, Mr McIver - both in their 30s - and an uncharged woman went to the complainant's Kambah house where she was at the front with her three children.

Just before the alleged assault, the complainant said she did not want trouble and Ms Williams threatened to grab one of the children if the complainant went inside.

Ms Williams then allegedly punched the complainant before the attack spilled inside the house, prompting the unknown woman to join in.

The complainant sunk into a foetal position with her hands on her stomach.

Mr McIver then came up the stairs and stood at the front door before he said "enough".

As the trio left, Ms Williams called out "you better end it with him".

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When police arrived, they found the complainant sustaining injuries to nose, lips, jaw, arms and hands.

The incident occurred the day after the complainant revealed on Facebook that she was expecting a baby with Ms Williams' ex-partner.

During the trial on Wednesday, CCTV clips of the trio arriving at the Kambah premises were played to the court.

The Crown argued that Mr McIver knew the other two were aggressively going up the driveway towards the victim.

But on Wednesday, defence lawyer Jan de Bruin said his client did not know there was going to be an assault and that he "simply did what he could" to put an end to it once it had started.

"He did everything in his power to remove himself and the others from the situation," Dr de Bruin said.

In his judgment regarding Mr McIver, Justice Michael Elkaim dismissed the Crown's argument that the accused's mere presence in the car indicated his guilt.

"There is nothing to suggest that until matters got out of hand at the residence that Mr McIver had any idea of what was to occur," Justice Elkaim said.

The judge said "mere knowledge" was not enough to dictate guilt and that "his manner of exiting the car, his casual ascent of the driveway, including smoking a cigarette, are equally consistent with him simply taking an inquisitive approach as to what was occurring".

The judge also said Mr McIver saying "enough" may have well said so because he thought matters were out of hand "whether or not he considered his appeal would have any effect".

"The Crown may be right in its interpretation of Mr McIver's actions as depicted in the CCTV. But 'may be right' is not enough," he said.

"Such a conclusion, while open, is only open on a somewhat speculative basis".

Following the acquittal, Mr McIver smiled then said "the justice system works".

Ms Williams' adjournment application was supported by a psychiatric report in which the author said she "was not aware enough to control the event or be aware enough to think about or contemplate the wrongness of her behaviour".

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