A lawsuit filed Tuesday in Los Angeles County Superior Court casts Nuala as "a greedy stage mother posing as a talent manager who, instead of acting in the best interest of her daughter/client, schemed to defraud her unsuspecting victim."
Mischa, now 29, entered into a verbal contract when she was 8, agreeing to pay her mother a management fee equal to 10% of her gross earnings but not more than that, the lawsuit says.
The actress "placed her utmost trust" in her mother until recently, when Mischa's discovery of "exploitation and fraud, coupled with ongoing instances of bullying and verbal abuse" resulted in the breakdown of their personal and professional relationships, the suit says.
According to the lawsuit, Nuala created various companies that gave her control over her daughter's money, gave herself half-ownership in the house Mischa bought in 2006 and then borrowed against that property, started her own side businesses making money off Mischa's image, entered Mischa into endorsement deals — one as recently as October — without explaining the obligations of those deals, and lied to her daughter about her salary to act in "The Hoarder" and pocketed the difference.
Nuala also lied to Mischa about how much the actress had been paid to do the movie "The Hoarder," forged her daughter's signature on documents associated with the job and then pocketed the difference for herself, the suit says.
"Neither Nuala nor Barton's father, Paul, has had a job independent of Barton in over a decade," the lawsuit says. "Instead, they sit back expecting their daughter's hard work and dedication to her craft to support their lifestyle. Both comfortably reside in the $7.8 million Beverly Hills home that was purchased with Barton's funds while Barton is not welcome at the property."
Mischa is seeking actual damages plus triple that in punitive damages as well as legal fees. While no dollar amount is specified, the document puts the sum in question at more than $25 million.
The younger Barton had a rocky time after becoming a star via "The O.C.," which ran from 2003 to 2006. In 2007, she was arrested on suspicion of DUI and ordered by the court to go to rehab and employ a sobriety coach. In 2009, she found herself on a four-day involuntary psych hold.
"It was a full-on breakdown," Barton told People in October 2013. "I was under enormous pressure."
Back then, however, she was cutting her U.K.-born parents some slack.
"They were thrust into this situation that was completely foreign to them," she told the magazine. "Nothing could prepare them to have their children jump into the overtly sexualized and crazy world of L.A."
Still, she told the mag that when she was a teen she had lots of people depending on her. "I asked to get out of jobs all the time," she said, "and the response was, 'No, you have to.' There's an attitude that you can't say no."
Mischa Barton is now represented professionally by agent Jonathan Perry of APA and manager Adam Griffin of LINK Entertainment. Lawyers Alex Weingarten and Leslie Eggers of Venable LLP are representing her in the suit against her mother.