As a trade dispute between former colleagues, coming to a compromise could have been child's play. But with $100m (£61m) at stake, the battle between Barbie and her younger rival, Bratz, has been long and bitter. Six years after it started, the squabbling is finally set to end.
Jurors will assemble in a California courtroom tomorrow to begin deliberations over whether the Bratz designer Carter Bryant developed the concept for the billion-dollar doll line while under contract as a Barbie designer at Mattel.
The copyright infringement and trade secrets trial brings to an end the longest legal battle of its kind, between Mattel and the developer of Bratz, MGA Entertainment. Mattel was awarded damages of $100m in 2008, but the jury's decision was later overturned. Mattel claims that MGA Entertainment conspired with Mr Bryant to steal the idea for the dolls while he worked for the company.
Barbie was launched in 1959 by the American businesswoman Ruth Handler. Mattel estimates that there are now over 100,000 Barbie collectors. The doll has faced widespread criticism for promoting an unrealistic body image to girls.
The hip-hop inspired urban Bratz dolls with their crazy hair styles and provocative outfits were launched in 2001, targeting the 'tween generation and knocking Barbie off her 50-year throne. In three years, Bratz were outselling Barbie in the UK.
Then came the legal cat fight. In 2008, a jury ruled that MGA Entertainment was liable for "conversion", a term for industrial theft. Alex Kozinski, the Appeals Court judge who overturned the decision, wrote: "Unlike the relatively demure Barbie, the urban, multi-ethnic and trendy Bratz dolls have attitude. America thrives on competition; Barbie will too."
But in court on Friday, Mattel's attorney Bill Price told jurors: "The case really is about building a brand by using another company's confidential information and ideas, and that's wrong."
MGA Entertainment's attorney denied the allegations. The Bratz maker has countersued Mattel for damages.
Jennifer Keller, who represents the firm, describes Mattel as a ruthless corporation bent on destroying anyone who threatens Barbie's dominance. "This case is about how the world's biggest toy company tried to crush the only competitor against Barbie," said Ms Keller.