A federal judge on Tuesday rejected a civil rights challenge in Britney Spears’s conservatorship case, allowing the pop star’s father to maintain his temporary control of her $100 million estate.

U.S. District Judge Philip Gutierrez returned the case to state probate court and sent a rebuke to the lawyer who launched the challenge, Jon Eardley, who had claimed to represent Spears.

“Mr. Eardley fails to explain why he can bring this claim for her in the first instance. He cannot,” Gutierrez said in his three-page ruling. “Mr. Eardley had no authority to remove the case from state court. He is neither a party nor a defendant. While he claims to be Ms. Spears’s attorney, the probate court … found that she was incapable of retaining her own counsel.”

The ruling was a victory for Spears’s father, Jamie, who was named as a temporary co-conservator of her estate by the California probate court after Spears was placed under an involuntary, emergency hold at the UCLA Medical Center’s psychiatric ward late last month.

As temporary co-conservator, Jamie has great influence over the pop star’s fortune as well as her day-to-day activities.

In a highly publicized move, Eardley, a lawyer with practices in Washington, D.C., New York and Whittier, Calif., filed a complaint in U.S. District Court on behalf of Spears. He lashed out against the conservatorship as a “violation of [Spears's] civil rights,” and requested the case be moved from California state court to a federal court.

Jamie Spears and the other temporary co-conservator, attorney Andrew Wallet, had called Eardley’s move “a brazen – but vain – attempt to strip a probate court of jurisdiction … by an attorney without a client.”

While the federal judge ruled in Jamie Spears’s favor, Britney ventured out for an afternoon shopping trip. Spears, accompanied by her assistant and a family friend, arrived at the Levi’s Store in Beverly Hills in a chauffeur-driven black Escalade ESV.

“Britney walked in to the store in jeans with a green top and a huge smile,” eyewitness Brenda Gold tells PEOPLE.

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