Three women who were sexually harassed by former High Court justice Dyson Heydon have secured a historic compensation payout.

The women's lawyer, Josh Bornstein, said he believed it was the first settlement under the Sex Discrimination Act for findings of sexual harassment against a serving federal judge.

The High Court apologised publicly to the trio — Rachel Patterson Collins, Chelsea Tabart and Alex Eggerking — as well as to three other unnamed women in 2020 after an independent investigation, led by Vivienne Thom, upheld their allegations.

Five of the women had worked as associates to Mr Heydon, while the other had worked for a different High Court justice.

After Dr Thom completed her inquiry, Chief Justice Susan Kiefel said the findings were of "extreme concern" to all of the court's justices and staff.

"We're ashamed that this could have happened at the High Court of Australia," she said in a statement.

Today, Mr Bornstein said negotiations since then had been delayed by the case's complexity and "an unfortunate delay by the Commonwealth".

“After their experience of working in the High Court, Rachael, Chelsea and Alex have been unable to pursue the legal careers that they aspired to," he said.

The terms of the settlement remain confidential.

However, Mr Bornstein said his clients were relieved and happy with the outcome.

"They have asked me to convey their strong conviction that women should not feel ashamed to pursue financial settlements in sexual harassment cases, because sexual harassment will only start to recede when there is a clear recognition that it has a substantial cost to organisations and individuals who are implicated."

Mr Heydon, now 78, has previously denied "any allegation of sexual harassment or any offence".

He was a High Court justice from 2003 to 2013, when he reached the mandatory retirement age.

Female associates have transformed court: Attorney-General

Federal Attorney-General Michaelia Cash praised the courage of the associates who had made formal complaints, saying they had instigated a transformation of the court's culture.

"We recognise Ms Tabart's, Ms Eggerking's and Ms Collins's bravery at coming forward and telling their stories to Dr Thom, the High Court and other Australians," Ms Cash said.

"These women have told us about what they have been through during, and since, their times as associates of the High Court and the serious impacts on their lives.

The government accepted all six of Dr Thom's recommendations and Ms Cash said it had acted on them.

"The practices of the High Court in responding to sexual harassment, and more importantly in attempting to prevent it from occurring, have been transformed."