Leighton, 25, who was famously born in prison to her mother, Constance, who was serving time after a drug smuggling conviction, is said to be "disgusted" that the Dh27,000-a-month allowance she gives to her mother for her brother Alexander's medical bills, is being spent on other things.
In her lawsuit against her mother, Leighton states that Alexander suffers from a myriad of health problems, and most recently underwent brain surgery on July 22, with the actress's paycheques supposed to be used to cover his medical bills.
"Leighton is disgusted by her mother and is determined to get her brother Alex out of that situation," an insider told RadarOnline.com. "She wants him to leave their mom's California home and come to live with her in New York, where she is based whilst filming her show, Gossip Girl."
‘Her mum won't work'
Sources claim that Constance - who used to be her daughter's manager - refuses to get a job, and believes it is her daughter's duty to give her a monthly allowance to live on.
"Although [Constance] is healthy and physically able to work, [she] refuses to do so," adds Leighton's lawsuit. "Instead, Constance expects her daughter to support her financially." While a pal adds, "Leighton is really close to her brother, so she just hates that she can't be there to help him more."
And sources claim that Constance used Alexander's allowance for Botox injections, cosmetic surgery and treatments, as well as other personal expenses.mother claims: ‘she Beat Me'
Fifty-five-year-old Constance is counter-suing her daughter, claiming that they had a verbal agreement in which Leighton promised to give her Dh36,000 a month for the rest of her life. And she now plans to sue Leighton for Dh11 million - also alleging her daughter beat her up, with celebrity news website, TMZ.com reporting Constance's claims that Leighton "repeatedly hit her with a bottle" after throwing her to the ground last December, and had to be pulled off by Alexander.
No longer her ‘inspiration'
Leighton's lawsuit is a far cry from her position last year, when during an interview she called Constance her "inspiration", adding, "She is an amazing woman."
"This whole thing's been really tough on Leighton," said a close friend. "Her only concern has always been taking care of her brother. Leighton's a sweet girl - she cares about work, friends and family."
From jail to Hollywood
Leighton's life is a classic rags to riches story, with the actress born in a Texan prison in 1986, where her mother was serving a jail sentence for her part in a drug ring. Now one of the most sought-after young actresses in Hollywood, Leighton last month landed a Dh11 million contract to be the new face of Vera Wang perfume, whilst her mother recently had a restraining order taken out against her for allegedly making death threats against a Californian woman and her son.