Pop singer Britney Spears lost custody of her children Sean Preston, 2, and Jayden James, 1, to ex-husband Kevin Federline because she failed to produce a valid California driver’s license as demanded by judge and allegedly missed a random drug and alcohol test, her lawyer said.

Britney Spears’ lawyer Sorrell Trope told People magazine, “We weren’t able to prove compliance with what the judge ordered.

“Specifically,” Trope said, “the judge ordered that by 10 a.m. (Monday) morning, both parties show valid California driving licenses. I’ve been unable to produce evidence of that.”

Another reason behind was a claim by Kevin Federline’s attorney that she had skipped a drug and alcohol test. “There’s no evidence that she actually failed a test,” Trope told the magazine.

Superior Court Commissioner Scott M. Gordon ordered Britney Spears to relinquish physical custody of her children to Federline “until further order of the court”; she and Federline still share legal custody.