A woman has been awarded Â£164,000 from her estranged mother's estate, even though the mother expressly stated in her will that she did not want her child to receive a penny.
Melita Jackson left her Â£500,000 estate to animal charities when she died in 2004.
But after an eight-year court battle, her only daughter, Heather Ilott, 54, was granted a third of that money on the grounds that her mother did not leave "reasonable provision" for her in the Will.
The Court of Appeal ruled that Mrs Ilott would otherwise face a life of poverty because she was on benefits and could not afford to go on holiday or buy clothes for her children
The fact that Mrs Jackson had little connection to the charities to which she left her money played a part in the ruling, the judges said.
This decision may make it far easier for adult children who are disinherited by their parents to challenge their Wills and gain a proportion of any estate, under the Inheritance (Provision for Family and Dependents) Act 1975.
Gary Rycroft, a member of the Law Society's wills and equity committee, said: "This ruling is saying that while you can still disinherit your children, you are going to have to explain why and show connections with those you are leaving the money to.
"It is also very important because it seems to be making it easier for adult children to claim for reasonable financial provision in wills and has made the gap wider for them to do that."
Previously the Courts have been reluctant to make awards to adult children who were estranged from their parents and were not financially maintained by them.
In this case the Court has placed a greater emphasis on the financial situation of the daughter, even though she was a grown woman with a family of her own, estranged from her mother for many years and not financially reliant upon her mother during her lifetime.
Mrs Ilott challenged the Will in 2007 under a right to "reasonable provision" which is contained in the 1975 Inheritance Act. It is normally used for young children who are left out of wills, but in 2011, Mrs Ilott won Â£50,000 from the estate before challenging for more money. She lost in the High Court last year but succeeded in the Court of Appeal.
Lady Justice Arden awarded her Â£164,000 to allow her to buy her housing association home in Ware, Herts, with Â£20,000 left over to supplement her benefits. The judges drafted the ruling so that she would not lose her state benefits.