Barbie firm Mattel hoping for £1bn in battle over dolls

Huge sums are at stake in Mattel's copyright infringement case, but in the Californian trial's final hours lawyers instead asked jurors to think like children and sparred over the placement of beauty moles and the plumpness of glossy, heart-shaped lips.

The jury ruled last month in the trial's first phase that the dolls' designer, Carter Bryant, came up with the Bratz concept while working for Mattel. The jury also found that Los Angeles-based MGA aided in the breach of contract, and its chief executive, Isaac Larian, played a role in the deal.

Jurors must decide what, if any, damages they should award Mattel and whether they should also award unspecified punitive damages.

In his closing arguments, Mattel attorney John Quinn said MGA owed Mattel at least £500 million in Bratz profits and interest, while Larian owed nearly $800 million (£430 million) for his complicity.

Quinn said the four original Bratz dolls were virtually identical to Bryant's conceptual sketches and that all other Bratz-related products and their profits also belonged to Mattel.

MGA has since made profits of nearly $778 million on Bratz, which exploded in popularity among tweens — girls aged seven to 12, he said. The highly stylised fashion dolls have oversized feet, heads and hands, curling lashes and huge, almond-shaped eyes daubed with exotic-coloured eyeshadow.

Sales of Barbie, a near right-of-passage in American girlhood, have slid since Bratz's Yasmin, Cloe, Jade and Sasha came on the scene seven years ago. US sales of Barbie were down 15% in 2007.

"In history, there have only been two successful fashion dolls, Barbie and Bratz, and Mr Larian and Mr Bryant stole one of those," Quinn said. "The numbers are what they are ... and the law says when you profit by taking someone else's confidential information, you have to give it back.''