Mattel Inc. didn't violate a LeapFrog Enterprises Inc. patent, a federal district court in Delaware ruled Thursday.
LeapFrog had sued Mattel unit Fisher-Price in October 2003, alleging that its PowerTouch toy infringed a patent related to LeapPad electronic books.
U.S. District Judge Gregory M. Sleet said Fisher-Price hadn't violated the patent.
The ruling comes after sales slumped 48% in LeapFrog's education and training unit and 29% in the international division in the fourth quarter of 2005. The LeapPad line accounted for 29% of revenue last year, down from 37% in 2004 and 47% in 2003, the Emeryville, Calif.-based company said in a regulatory filing this month.
LeapFrog had claimed that Fisher-Price copied the technology from LeapPad books that lets children press the letters of a word to hear how they sound. LeapFrog sought $58 million in damages. El Segundo-based Mattel said that its PowerTouch books used different technology and that the LeapFrog patent was invalid.