'Britney lives in a parallel universe,' blasts lawyer after singer fails to attend 8 out of 14 drug tests

Federline's attorney Mark Vincent Kaplan told Superior Court Commissioner Scott Gordon that there have been 14 laboratory requests for drug testing and Spears failed to respond to eight of them.

Mr Kaplan claimed the singer lives in a "parallel universe".

"Mr Federline doesn't want to take these children out of their mother's life, but what are we to do?" Kaplan said.

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Federline has temporary custody of the couple's two children, two-year-old Sean Preston and one-year-old Jayden James.

Anne Kiley, Spears's lawyer, argued the previous court order was unconstitutional and Spears did not respond to the lab phone calls within an hour, as ordered by the court, because she was sleeping.

Kiley asked that Spears be given six hours to respond to the laboratory phone requests.

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But the judge said time was not the problem and noted that Spears has lost telephone numbers and changed her telephone numbers.

He suggested Spears get a separate cell phone for lab-only use.

LA family law attorney Joel Schwartz, who has been following the case, told People magazine: "If Spears hasn't been following drug-testing procedures, ultimately the court could suspend all her visitation rights until she follows court orders."

"Her mistakes will stack up against her."

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Spears's court-appointed parenting coach has been critical of her mothering skills, which resulted in her visitation rights with her sons.

Spears "rarely engaged with her children [Sean Preston, two, and Jayden James, one] in either conversation or play," according to a report filed last month.

Meanwhile, Spears's judgement has again been called into question after she splashed out on two-seater sports model, despite the fact it's not particularly child-friendly.

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The pop princess, who was photographed driving with Sean Preston on her lap last year, has been banned from driving him or his brother Jayden James, aged one, unless they are in child safety seats.

Perhaps she was considering this as she inspected the 4x4.

But Spears, 25 - whose single Gimme More is at No7 in the charts - must have decided it just wasn't her and plumped for a £120,000 white SL 65 model.

Onlookers might have been surprised she could afford to fork out such a huge amount after she was ordered to pay her ex-husband Kevin £110,000 legal fees for their custody battle over the boys. She already pays K-Fed £7,500 a month in child support.

But revelations this week perhaps show why Spears is not more angry about supporting K-Fed.

Spears's former assistant Kalie Machado has told how the 25-year-old set up a shrine to Kevin Federline after they split and also revealed Britney would regularly walk around her home naked.

Kalie reveals that Britney struggled to cope with the breakdown of her marriage, and as well as keeping her wedding dress in a case in the entrance of the home, also held on to Kevin's possessions.

She revealed: "Britney kept all Kevin's clothes and she would wander into his wardrobe and look at them. You could say it was a shrine to him - or to their marriage at least."

Kalie claims that during her marriage, Kevin was hardly ever home, leaving Britney alone with her sons and while she eventually filed for divorce, she was still desperate to win back his affection.

Kalie said: "She felt so unwanted and she's already insecure. It just made her crazy and depressed.

"She was incredibly sad and lonely while I was with her. I could tell she desperately wanted him back. She'd burst into tears when he wouldn't return her calls."