A jury has decided that Samsung must pay Apple $539 million in damages for illegally copying some of the iPhone's features to lure people into buying its competing products.
The verdict is the latest twist in a legal battle that began in 2011.
Apple contends that Samsung wouldn't have emerged as the world's leading seller of smartphones if it hadn't ripped off the technology powering the pioneering iPhone in developing a line of similar devices running on Google's Android software.
Previous rulings had already determined that Samsung infringed on some of Apple's patents, but the amount of damages owed has been hanging in legal limbo.
A jury convened for the original 2012 trial had determined that Samsung should pay Apple $1.05 billion.
A jury in a 2014 trial found that Apple had infringed on some of Samsung's patents, and decided Apple should pay approximately $158,400 in damages, while at the same time declaring that Samsung needed to part with $119.6 million.
Eventually, US District Judge Lucy Koh pegged the amount to be paid by Samsung as $548 million.
The issue was escalated to the US Supreme Court, which determined in 2016 that a lower court needed to re-examine $399 million of the $548 million.
That ruling was based on the concept that the damages shouldn't be based on all the profits that the South Korean electronics giant had rung up from products that copied the iPhone, because its infringement may only have violated a few patents.
Apple had argued it was owed more than $1 billion while Samsung contended the $399 million should be slashed to $28 million. The revised damages figure represents a victory for Apple, even though it isn't as much as Cupertino had sought.
"We will consider all options to obtain an outcome that does not hinder creativity and fair competition for all companies and consumers," Samsung said today in a statement.
An eight-person jury came up with the new amount following a one-week trial and four days of deliberation.
Apple expressed gratitude to the jury for agreeing "that Samsung should pay for copying our products".
"This case has always been about more than money," a company statement said.
"Apple ignited the smartphone revolution with iPhone and it is a fact that Samsung blatantly copied our design."
During the trial, Apple attorney Bill Lee stressed the importance of design, saying Apple "puts design before everything else". The design patents that Samsung infringed concern the physical shape that would become the iPhone, the bezel, and the colorful grid of icons.
Samsung attorney John Quinn held up components to the jury, emphasising that each was its own article of manufacture, and that there are "hundreds of articles of manufacture inside a phone".
"The only way Apple can come up with $1 billion in damages is by saying the article of manufacture applies to the whole phone," Quinn said. "None of the patents is the whole phone."
On the flip side, Apple was ordered to pay $506 million for patent infringement to the University of Wisconsin-Madison's patent licensing arm in 2017.
Originally set at $234 million by a federal jury ruling in 2015, the damages were raised due to Apple's continued infringement of the patents until December 2016.
The patent in question was gained in 1998, and related to predicting user input. At the time, it was reported that Apple would appeal the decision.
Last year, Samsung also lost a patent dispute against Chinese smartphone manufacturer Huawei, in a case dealing with user interface elements such as widget design and how icons are arranged.
In March, the European Patent Office revealed that Huawei had filed the largest number of patents with it, being responsible for 2,398 patent applications during 2017 out of a total of 166,000, which represented an all-time high for the office.
"Huawei places great emphasis on research and development, so the creation of high patent numbers is a natural result," said Dr Song Liuping, Huawei senior vice president and chief legal officer. "These numbers may rise further as we increasingly participate in the setting of next-generation telecommunication standards such as 5G."
Huawei had filed 64,091 patent applications in China and 48,758 outside of China as of the end of last year.
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