A mistrial was declared on Friday in LeapFrog Enterprises Inc.’s lawsuit against Mattel Inc.’s Fisher-Price unit after a jury couldn’t decide whether Fisher-Price copied electronic book technology patented by LeapFrog.

U.S. District Court Judge Gregory M. Sleet, who is now expected to decide the case, made the mistrial ruling in Wilmington, Del. LeapFrog is seeking up to $78 million in damages.

LeapFrog, based in Emeryville, makes an electronic book called a LeapPad that allows children to push letters and hear how a word sounds. LeapFrog claims that Fisher-Price’s electronic book, the PowerTouch, is based on the technology used in the LeapPad, a claim that Mattel rejects.

Michael Milken, the former junk bond king, and his brother Lowell Milken were among a group that included Oracle Corp. Chief Executive Larry Ellison who received more than 8 million shares of LeapFrog last year. El Segundo-based Mattel manufactures Barbie and is one of the world’s largest toy companies.