Apple just took another hit in its yearslong fight with medical device maker Masimo. A California federal judge upheld a jury’s $634 million verdict against the tech giant. The ruling, issued late Monday, rejected Apple’s attempts to toss the damages or force a new trial. Short and simple. The decision locks in liability for patent infringement tied to Apple Watch features.
But the story runs far deeper. It stretches back to 2020, when Masimo first accused Apple of swiping trade secrets and copying pulse oximetry technology. That suit spawned multiple fronts. One landed at the International Trade Commission. Another played out in California district court. Outcomes varied. Some favored Masimo. Others tilted toward Apple. This latest chapter, however, hands the smaller company a major financial victory that could influence how big tech approaches health sensor patents.
The jury spoke clearly in November 2025. It found Apple infringed Masimo’s U.S. Patent No. 10,433,776. The claims cover optical sensors that measure blood oxygen levels. Specifically, the Apple Watch’s workout mode and heart rate notifications crossed the line, according to the verdict. Damages reached $634,313,913. Exact figure. No rounding. That award now stands.
Judge James V. Selna didn’t buy Apple’s core argument. The company insisted its smartwatch didn’t qualify as a “patient monitor” under the patent’s terms. Conventional hospital gear, Apple claimed, fit the definition. Not a consumer device strapped to someone’s wrist during a run. Selna disagreed. He sided with the jury’s view that the patent’s language embraced a broader, everyday meaning. The Apple Watch, in other words, counts.
Apple also pushed for judgment as a matter of law. It challenged the court’s construction of key claim terms. It attacked jury instructions. It complained about the exclusion of certain expert testimony. None of it moved the needle. Selna found no errors grave enough to justify a retrial. The verdict holds. Apple plans to appeal, of course. It said so immediately.
“Masimo is a medical device company that does not sell any products to consumers,” an Apple spokesperson told Reuters. “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.”
Masimo struck a different tone after the original verdict. “This is a significant win for Masimo in our efforts to protect our intellectual property,” the company said in a statement reported by Reuters. The message was clear. Years of litigation finally delivered real money.
The dispute’s roots run to pulse oximetry. Masimo built its reputation on accurate, motion-tolerant blood oxygen readings. Hospitals rely on its gear. When Apple launched the blood oxygen app on the Apple Watch Series 6 in 2020, Masimo cried foul. It alleged Apple poached engineers and lifted proprietary algorithms. A separate trade secrets trial ended in mistrial in 2023. Jurors deadlocked. That claim largely fizzled, though the judge later found Apple misappropriated two of 14 alleged secrets.
Parallel action at the ITC proved more dramatic. In 2023, the trade tribunal banned imports of Apple Watch models with the blood oxygen feature. Series 9 and Ultra 2 sales halted briefly. Apple redesigned the software. It offloaded some calculations to the paired iPhone. The feature returned in 2025. Masimo challenged the workaround, suing U.S. Customs and Border Protection. A preliminary ITC ruling in March 2026 sided with Apple’s redesign. No new ban. Yet the patent case in California followed its own track.
That separation mattered. The $634 million verdict targets a different Masimo patent than the ITC matter. It focuses on heart rate notifications and workout modes rather than the full blood oxygen app. The patent expired in 2022. Too late to block future sales. But the damages cover past infringement. Apple sold millions of watches with the features. The jury did the math.
Legal watchers note the ruling’s implications. Big tech pours billions into health sensors. Accuracy claims drive marketing. Patents in this space can carry real weight, even against giants. 9to5Mac first broke the news of Monday’s decision to a wide audience. It highlighted how Selna upheld the jury on the patient monitor question. The judge’s opinion emphasized the patent’s plain language. Everyday use. Not limited to clinical settings.
Recent coverage adds context. Law360 detailed the post-trial motions in depth. Apple sought to undo the claim construction. It wanted a new trial on damages. Selna said no on both. His order, issued July 20, 2026, entered final judgment mostly in Masimo’s favor on the patent claims. Trade secrets findings split. Apple prevailed on most of those.
Meanwhile, Masimo itself changed hands. Danaher Corp. closed its $10 billion acquisition of the company in June 2026. The deal adds heft. Masimo gains resources to press its case through appeals. Apple, for its part, shows no sign of backing down. It continues to tout its own innovations in health monitoring. WatchOS updates refine ECG, irregular rhythm alerts and temperature sensing. Blood oxygen remains disabled on new U.S. models sold after the ITC ban, pending further legal clarity.
The fight underscores tensions in wearable tech. Consumers expect medical-grade accuracy from devices that also play music and take calls. Regulators scrutinize health claims. Patents become weapons. Masimo spent decades perfecting signal processing to filter motion artifacts. Apple scaled that concept to millions of wrists. Whether it crossed into infringement is now a matter for higher courts.
And the clock ticks. The infringed patent is dead. Future Apple Watches won’t face damages under it. But the precedent could shape licensing talks across the industry. Other sensor firms may dust off old IP. Tech companies might audit their supply chains more closely. Or they might double down on in-house development to avoid similar payouts.
Either way, this verdict won’t fade quietly. Apple will appeal to the Federal Circuit. Arguments will revisit claim construction, jury instructions and damages calculations. Masimo will defend its win. The saga, already six years old, could stretch several more. For now, though, the score reads clear. Masimo gets the money. Apple gets the bill. And the wearables patent wars roll on.
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