A Wisconsin jury found Tuesday that Apple Inc. used technology in its most popular devices without permission, Reuters and the BBC reported.
The company could face up to $862 million in damages over the patent by the University of Wisconsin-Madison that improves processor efficiency.
The amount will be determined at a later stage in the trial, the BBC said.
Reuters said representatives for the patent holder and Apple could not be reached for comment.
The Wisconsin Alumni Research Foundation sued the tech giant in 2014.
The jury was tasked with deciding whether the chips in the iPhone 5s, 6 and 6 Plus, and several iPad versions, violated the patent.
Apple argued that the patent was invalid, Reuters said. The U.S. Patent and Trademark Office denied the company's bid for a review of the patent.