Tensions laid bare: Former judge Mary Gaudron.

Tensions laid bare: Former judge Mary Gaudron. Photo: Wolter Peeters

For 16 years Mary Gaudron was a judge in the highest court in Australia, sitting on landmark cases such as Mabo and Wik and earning a reputation as a passionate advocate for equality and human rights.

But last week the former judge sat in the public gallery as details of estrangement between her and her younger sister, Helen Underwood, were raked over in a bitter dispute over their mother's modest estate.

Grace Gaudron, known as Bonnie, died in August 2010, leaving a unit in Birrong, in south-west Sydney, which was sold for about $360,000 and divided between Mary and her sister Kathryn, according to the terms of the will.

But Ms Underwood, who changed her name from Margaret to Helen some years ago, and Grace's youngest child, Paul, were specifically excluded from the will. Both were estranged from the family. In Ms Underwood's case, she had not seen her mother for 20 years.

Ms Underwood, a pensioner from Brisbane who lives in a housing commission unit, is seeking a share of the will under the Family Provision Act. She claims to have physical and mental health problems and says the will does not provide for her needs.

The NSW Supreme Court will overturn the wishes of a testator if the person excluded from the will is a wife, husband, child or other dependent and judged to be needing of support.

Ms Underwood says she moved back in with her mother in the mid 1980s after an acrimonious divorce and messy custody battle but was evicted by Grace. The court heard Ms Underwood threw a cup of coffee on her mother in 1987 and apart from one meeting at a wedding in the 1990s, they had no further contact with each other.

Mr Gaudron also lost contact with his mother and sisters in the late 1990s after his marriage broke down. He lost his leg in a train accident in 1964 and after 15 years working on the railways became an invalid pensioner about the same time as his much acclaimed elder sister was appointed to the High Court in 1986.

Justice Philip Hallen was told Ms Gaudron paid her brother $80,000 from her share of the estate to avoid litigation after learning he was going to make a claim.

But Ms Underwood's request for $100,000 was rejected and the sisters have each spent about $35,000 on legal fees fighting it out.

Ms Underwood contends she lived in the shadow of her gifted older sister, Mary, who won the Sydney University law medal and went on to become a Queen's counsel, solicitor general, a federal court judge, and ultimately the first woman on the High Court.

She only became aware her mother had died 15 months after the event after finding a death notice online. Under the Succession Act, an eligible person must make an application for a family provision order within 12 months of the date of death.

Her barrister, Therese Catanzariti, said Ms Underwood did seek legal advice once she became aware of Grace's death but was told she was out of time.

Months later she discovered she could make an application to overcome the time limitation, Ms Catanzariti said. She is seeking $55,000 plus costs.

However Brian Skinner, for Ms Gaudron, refuted Ms Underwood's explanation for the delay, arguing she displayed an "I did what I did in my own time and to hell with the rest of you" attitude towards the court's rules.

"It's the same attitude towards the breakdown of the relationship with her own mother," Mr Skinner said.

Justice Hallen reserved his decision.