Tech giant Apple has been ordered to pay $532.9 million in damages after a federal jury found it guilty of wilful patent infringement.
The jury, sitting in the US District Court for the Eastern District of Texas, took eight hours to decide that Apple's iTunes software infringed three patents belonging to licensing firm Smartflash.
It is thought that Smartflash had asked for $852 million in damages for Apple's willful infringement of the patents, which have been described as covering portable data carriers and computer networks for payment information storage, access, management and validation.
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Apple promised to appeal.
"We refused to pay off this company for the ideas our employees spent years innovating and unfortunately we have been left with no choice but to take this fight up through the court system," Apple said in a statement.
Smartflash filed its patent infringement complaint against Apple in May 2013.
It accused Google, Samsung and HTC in the same month.
The jury agreed with Smartflash's argument that Apple used software based on ideas patented by inventor and Smartflash executive Peter Racz, without permission.
According to court documents, Apple senior director Augustin Farrugia learned of the technology claimed in the patents when named co-inventor Patrick Racz met with executives of what is now SIM card maker Gemalto in 2000.
Apple has lost two previous patent cases in the Eastern District of Texas and successfully appealed both of them.
