A federal jury in California ruled Friday that Apple must pay medical device maker Masimo $634 million for infringing a patent on blood oxygen monitoring technology.

Reuters reports that the jury found that the Apple Watch’s workout mode and heart rate notification features violated Masimo’s patent.

“This is a significant win in our ongoing efforts to protect our innovations and intellectual property, which is crucial to our ability to develop technology that benefits patients,” Masimo said in a statement. “We remain committed to defending our IP rights moving forward.”

An Apple spokesperson told Reuters that the company plans to appeal the verdict, adding, “The single patent in this case expired in 2022, and is specific to historic patient monitoring technology from decades ago.”

TechCrunch has reached out to Apple for additional comment.

The legal dispute between Masimo and Apple focuses on pulse oximetry, which uses an optical sensor to detect blood flow. Masimo has accused Apple of hiring away its employees — including its chief medical officer — and infringing its patents on pulse oximetry technology. 

The U.S. International Trade Commission sided by Masimo in 2023, banning Apple from importing Apple Watches with blood oxygen monitoring features — which is why Apple Watches have not supported blood oxygen monitoring in recent years.

Then Apple announced in August of this year that it’s introducing a new version of the feature designed to circumvent the ban, with blood oxygen readings measured and calculated on the user’s paired iPhone, rather than the Apple Watch itself.

Masimo is suing U.S. Customs and Border Patrol for approving the import of Apple Watches with the new blood oxygen implementation, while Apple has asked an appeals court to overturn the import ban.

Apple also countersued Masimo, winning the statutory minimum payment of $250 when a jury found that Masimo had violated Apple design patents.