The legal woes of the Apple Watch are continuing, as Apple has been hit with a $634 million verdict in a trial over alleged infringement of Masimo's blood oxygen monitoring patents.

Masimo has repeatedly gone after Apple, believing that the iPhone maker has used its patents in the Apple Watch to detect a user's blood oxygen levels. On Friday, a federal jury agreed with Masimo and ruled that Apple pays $634 million in compensation.

The trial, which concluded on Friday with the ruling, saw jurors agree with Masimo that heart rate notification features and the Apple Watch's workout mode violated Masimo's patents, reports Daily Journal.

Definitions

The lawsuit was decided mostly on the basis of whether the Apple Watch could be considered a "patient monitor," which would mean Masimo's patent would more directly apply to the wearable. Apple insisted that the term was meant to refer to clinical monitoring equipment that is made not to miss critical medical events.

Apple's legal team reasoned that the design of the feature in the Apple Watch meant it would only trigger if the user is motionless for ten minutes. This, therefore, wasn't satisfying the continuous element of the definition.

Masimo told jurors to consider Apple's own descriptions of the Apple Watch, as well as its use by physicians and patients. At one point, Masimo mentioned internal Apple documents referring to the Apple Watch as "the most used heart rate monitor in the world."

When it came to technical comparisons, Masimo insisted that the Apple Watch detects the event of a high heart rate at rest with 95 percent accuracy. This, Masimo reasoned, met the requirements of the patent.

Apple countered by saying that the Apple Watch performed different functions for users than a clinical monitor. Therefore, it shouldn't be considered as a patient-monitoring device for the purposes of the patent.

Masimo also pointed to Apple's refinement of high heart rate notifications after learning of Masimo's patent, rather than reverting to an earlier method. The lawyers asked why Apple wouldn't just go back to the previous method if it was just a refinement.

Ultimately, the jurors sided with Masimo on the matter, in that Apple incorporated pulse-oximetry features into 43 million devices.

As for the award level, which is one of the largest for consumer technology in the Central District of California, the royalty figures are at the bottom end of Masimo's requested range, which maxed out at $749 million. Apple, meanwhile, believed that damages should be limited to between $3 million and $6 million.

Following the verdict, Masimo provided a statement to AppleInsider calling it 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."

An Apple spokesperson contacted AppleInsider to say the company disagrees with the verdict, and signaled an intention to appeal. The statement follows in full:

We disagree with today's decision, which we believe is contrary to the facts. Masimo is a medical device company that does not sell any products to consumers. Over the past six years they have sued Apple in multiple courts and asserted over 25 patents, the majority of which have been found to be invalid. The single patent in this case expired in 2022, and is specific to historic patient monitoring technology from decades ago. We plan to appeal.

The saga continues

The lawsuit is the latest salvo in a continued battle with Masimo over the Apple Watch. Over the years, Masimo has clashed with Apple with the International Trade Commission and in U.S. District Courts over the infringement claims.

This includes one billion-dollar attempt in 2023 that ended up being a mistrial, seemingly due to a lack of a unanimous verdict from jurors.

The ITC fight resulted in an import ban in the United States, which Apple countered by disabling the blood oxygen feature via software.

The lawsuits haven't just been against Apple's hardware. In October 2024, a jury found Masimo guilty of infringing Apple's health technology patents, resulting in a token payment of just $250 in damages.

The latest lawsuit result follows just after the U.S. ITC issued an order to restart an investigation into the Apple Watch and potential patent violations.

Updated November 15, 2025 at 11:39 P.M. Eastern Added full statement from Apple.