The woman has admitted to a second illegal data breach involving another of her romantic partners, who has since been sent to prison over child sex crimes.

On Wednesday the woman appeared at Port Kembla Local Court, where she pleaded guilty to two counts of using her position within the Department of Communities and Justice to illegally access restricted data.

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The department received complaints last year, alleging the woman had passed on confidential information in the two unrelated cases.

The court heard she began a relationship in November 2018 with a man who had been charged earlier that year over a violent domestic disturbance allegedly involving his previous partner and children.

The caseworker had moved in with the man and was at his side when he was arrested in February 2019 over other domestic-related allegations.

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An audit showed she accessed the records of the man's children without authority in February and November last year.

She is accused of passing on information about a Helpline report from April 2018, involving one of his children.

In order to protect the identity of those children, the Mercury is unable to name the caseworker, who had ten years' experience before she became the subject of an internal investigation. The investigation was ongoing when her employment with the department "ceased" this April. The department then contacted police, who found messages showing the woman had shared the illegally-won information with her partner.

Police also gathered social media messages between the pair, in which they discussed a record she had seen relating to an incident involving the man's children.

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The man has been charged with two counts of intentionally choking a person, and two counts of common assault. He denies any wrongdoing and will defend himself in court later this month.

The second breach relates to a man the caseworker had an affair with in 2018, while she was also involved in her ongoing relationship. She used the department's system to access information about that man twice and allegedly disclosed confidential details to him the following year, while he was in jail. The man was sentenced to six years' imprisonment, with a no-parole period of four years, for child sex crimes.

In court Wednesday the woman's lawyer, Anthony Williamson, said his client's first breach amounted to a "mistake", and said the information that had been passed on "didn't go into specifics".

The second breach was committed out of concerns the women held over the man having had access to her children through sporting activities, Mr Williamson said.

"She had a relationship wtih him. She accessed the information because she heard through the grapevine that he had been charged with some sexual offences," he said.

"She said communication with him was along the lines of, 'what have you done?', rather than 'here's some information that might help you'. She hasn't disclosed any confidential information to him."

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Magistrate Douglass noted that, despite her guilty pleas, the woman's account of events was different to that put forward by police, on the question of what she did with the information she illegally accessed.

"These sorts of offences are very serious and the court would want to not only deter this person, but deter others from commiting this type of offence," Magistrate Douglass said.

"What I'm trying to do is calculate how serious the situation is."

The matter was adjourned to October 7, for submissions on this, before the woman is sentenced.

She earlier told police she was extremely embarrassed by her actions and regretful of the situation.

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