'Britney Spears' drug use got so bad she spent night sleeping in a parking lot' claims ex-manager Sam Lufti, as he takes pop star to court for 'unpaid earnings'

An ongoing legal battle between Britney Spears and one-time manager Sam Lufti over whether or not he's owed commissions from the time he worked for her is heading back to court.

And among paperwork filed by the pop star's legal team is a 2015 ruling by the California Court of Appeals confirming that Britney was a drug user back in 2007-08, TMZ reported Tuesday.

The Appeals Court decision described how her abuse of illicit substances was so bad that on the day she lost custody of the two young sons to ex-husband Kevin Federline, she ended up sleeping in a parking lot.

Headed to trial: Britney Spears, pictured at LAX in March, is scheduled to be deposed as part of a breach of contract lawsuit brought by her former manager Sam Lufti. Her legal team want him barred from the deposition

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At the time Lufti and Britney met, the star was going through a messy divorce from Federline and was estranged from her parents.

She was also, the judges wrote, 'struggling with drug abuse.' Lufti claims he only agreed to manage her if she agreed to stop using drugs.

Svengali or friend? Lufti entered the pop star's life in 2007 when she was estranged from her parents and going through a messy divorce from Kevin Federline. The pair are pictured together in November 2007

Meltdown: As a 2015 ruling by the California Court of Appeals reveals, in 2007 and 2008 the pop star was abusing drugs. She's pictured in February 2007 in the LA suburb of Tarzana after shaving her head

Her parents, Lynne and Jamie, however, have long pointed the finger at Lufti who, they say, supplied their daughter with drugs.

Lufti sued Lynne Spears for defamation following the publication of her book Through The Storm. That suit was tossed out of court before it could come to trial.

But last year the California Court Of Appeals ruled that the decision to toss out his defamation lawsuit against Lynne in late 2012 did not prevent him from seeking financial redress for monies he claims he is still owed.

Lufti has filed a breach of contract suit against his former friend who he says turned to him for help in 2007 and asked him to be her manager.

And as part of the process, Lufti's team is preparing to depose the pop star. However, her legal team has filed documents requesting Lufti himself be barred from the deposition, and the 2015 ruling is included among that paperwork.

Lufti contends that he agreed to manage Britney if she got clean and granted him 15 percent of her earnings during the time he was her manager, according toThe Hollywood Reporter.

The judges, as reported by TMZ, decided that Britney had asked Lufti to manage her and that he had accepted on the condition that she let him put together a team and she would stop abusing drugs.

Lufti had also insisted on the right to use drug sniffing dogs to make sure she stayed clean. The judges said that despite her promises, Britney continued to use drugs.

Eventually, in 2008, her father Jamie got a court-approved conservatorship of Britney after she was forcibly admitted to a psych ward for evaluation at the end of January 2008. She has since bounced back in her career and her personal life.

Back on track: Since her highly publicized troubles and under the guidance of her father, Britney has rebuilt her career and is currently has her Piece Of Me residency in Las Vegas

Hands on mom: She now shares custody of her sons Sean, 10, and Jayden, nine, with Federline. On Tuesday, she posted this pic of them on her Instagram with the caption: 'No homework! Best day ever!'