Masimo wins $634M verdict against Apple in patent fight over Apple Watch

U.S. District Judge James V. Selna

SANTA ANA -- A federal jury on Friday awarded Masimo Corp. $634 million in its closely watched patent battle with Apple Inc., finding that all four asserted claims of Masimo's pulse-oximetry patent were infringed and concluding that certain Apple Watch models legally qualify as "patient monitors."

The sweeping verdict caps a yearslong fight over whether Apple misappropriated medical-grade monitoring technology and integrated it into consumer wearables sold between 2020 and 2022.

Jurors accepted Masimo's position that Apple incorporated its patented pulse-oximetry features into roughly 43 million watches, rejecting Apple's argument that any damages should be limited to between $3 million and $6 million. Masimo had sought royalties ranging from $634 million to $749 million. The verdict represents one of the largest patent awards ever returned in the Central District of California involving consumer technology.

The dispute centered on a single issue of claim construction: whether an Apple Watch can be considered a "patient monitor" for purposes of Masimo's patent. Throughout trial, Apple's counsel, Joseph J. Mueller of WilmerHale, argued the term refers only to devices designed for continuous clinical monitoring that cannot miss critical medical events. "The essential characteristic of all patient monitors is that they cannot miss important medical events," Mueller told jurors, insisting the Apple Watch's design--which triggers alerts only when a user is motionless for 10 minutes--could not satisfy that definition.

Masimo's attorney, Brian C. Horne of Knobbe Martens, urged jurors to focus instead on Apple's own descriptions of its device and its widespread use among physicians and patients. "Every single Apple Watch ever sold has been a heart rate monitor," Horne said, pointing to Apple internal documents calling it "the most used heart rate monitor in the world." He argued that Apple's technical expert conceded every element of the claim was met except for the disputed "patient monitor" phrase, which Masimo said Apple effectively embraced in practice.

Technical comparisons between the devices became a focal point of the trial. Masimo contended the watch detects a specific physiological event--a high heart rate at rest--with 95 percent sensitivity and therefore meets the patent's requirements. Apple countered that its device performs a fundamentally different function than clinical monitors and cannot be treated as a patient-monitoring device under patent law.

Jurors also heard evidence about Apple's decision to refine its high-heart-rate notifications rather than revert to an earlier version after learning of Masimo's patent. "If this was only a mere refinement, why don't they just go back?" Horne argued, suggesting that Apple's improvements signaled the feature's importance.

The case has a lengthy procedural history. U.S. District Judge James V. Selna stayed Masimo's patent claims for two years while validity questions were resolved, ultimately reinstating them in 2022. Masimo's separate trade-secrets lawsuit against Apple ended in a mistrial in 2023 and awaits retrial. The International Trade Commission also issued an import ban earlier this year after finding Apple infringed Masimo's patents, prompting Apple to redesign certain watch models.

Apple is expected to challenge the verdict, which could have significant implications for how courts assess quasi-medical features in consumer wearables. For now, Masimo has secured a major victory in its long-running campaign to hold Apple liable for allegedly leveraging its technology to dominate the digital-health market.