A federal court in Delaware ruled that Mattel Inc. and its Fisher-Price subsidiary did not infringe on a patent held by LeapFrog Enterprises Inc., and that the claim in question was found to be invalid.

The ruling was handed down Thursday. Mattel announced the decision on Friday.

The lawsuit was originally filed by Emeryville-based LeapFrog in October 2003 and related to Fisher-Price’s PowerTouch toy, an interactive book that helps children learn reading and other skills.

LeapFrog makes an electronic book called a LeapPad that allows children to push letters and hear how a word sounds. LeapFrog claimed that Fisher-Price’s electronic book is based on the technology used in the LeapPad, a claim that Mattel rejected. LeapFrog had been seeking up to $78 million in damages.

“As a company that invests significantly in the development of innovative products and intellectual property, we respect the intellectual property rights of others and conduct our business with the utmost integrity,” Neil Friedman, president of Mattel Brands, said in a statement after the ruling.

LeapFrog in a statement on Thursday said it would continue to defend its intellectual property rights in the future.

Last May, a mistrial had been declared after a jury couldn’t decide whether Fisher-Price copied the technology patented by LeapFrog.