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A California federal jury delivered a seismic blow to Apple Inc. on Friday, ordering the tech giant to pay more than $634 million to Masimo Corp. after determining that the Apple Watch infringed a pulse oximetry patent tied to its abnormal heart-rate alert feature. The verdict capped an eight-day trial but marked only the latest flashpoint in a sprawling, yearslong legal war between the two companies.

The panel deliberated for roughly three hours before unanimously concluding that Apple violated all four of the asserted patent claims — landing Masimo the exact low-end figure of the $634 million to $749 million royalty range it sought.

A Long-Simmering Feud Reaches a Boil

The decision intensifies a bitter feud that has already stretched across courts, agencies, and continents. This chapter focused on a single Masimo patent that the company said Apple cannibalized to fortify the health-monitoring functions of its blockbuster smartwatch.

Neither legal team offered immediate comment as they exited the courtroom, but the testimony left little doubt that the companies viewed the case as a clash over the future of wearable health technology.

Masimo: Apple Watch Is a Patient Monitor in Disguise

During closing arguments, Masimo attorney Brian C. Horne of Knobbe Martens said Apple’s entire defense rested on “one fragile plank”—the insistence that the Apple Watch is not a “patient monitor” under the patent’s definition.

But Horne told jurors they had seen ample evidence that the device acts exactly like one: marketed as a health monitor, functioning like one, and dependent on Masimo’s patented pulse oximetry technology to deliver a critical heart-rate warning feature.

Horne reminded jurors of his prediction in opening statements: Apple would dodge the technical comparisons and instead latch onto semantics.

“The Apple Watch is designed to monitor a user’s pulse rate — that’s the monitor this claim requires,” Horne said. “The evidence was overwhelming.”

Apple: A Smartwatch Is Not a Medical Device

Apple’s lawyer, Joseph Mueller of WilmerHale, countered that the patent targets traditional patient monitors — devices that gather continuous data in medical settings — whereas the Apple Watch only triggers the disputed feature when a user is still for at least 10 minutes.

To illustrate, Mueller joked that emergency medics would hardly consult a tiny smartwatch screen instead of a legitimate medical monitor.

If the Apple Watch is not a patient monitor, he said, “it cannot meet the claim language.”

Billions in Sales, Years of Litigation

Masimo based its royalty calculation on $14.72 to $17.39 per device across more than 43 million Apple Watches sold. The infringement window runs from the 2020 filing of the suit until the patent expired in 2022.

This case is part of a larger legal saga. Masimo accused Apple of poaching employees, stealing trade secrets, and copying its medical-grade sensor tech. Their dispute has snaked through multiple venues, including:

• U.S. International Trade Commission, which in late 2023 found Apple violated two Masimo patents and issued a limited import ban.

• U.S. Customs and Border Protection, which approved an Apple Watch redesign disabling the blood-oxygen feature to sidestep the ban.

• The Federal Circuit, which heard arguments in July over Apple’s redesign.

• D.C. federal court, where Masimo also sued CBP over its handling of the dispute.

A separate trade secrets trial in 2023 ended in a hung jury leaning 6-1 for Apple. Masimo’s patents were excluded then because Apple challenged them before the Patent Trial and Appeal Board; most were invalidated, but two survived. Masimo dropped one, and the remaining one  went before the jury last week.

U.S. District Judge James V. Selna split the trade secrets and infringement issues into separate proceedings; a bench trial on the trade secrets claims wrapped in February and remains undecided.

Doctrine of Equivalents Looms Large

Horne told jurors they could still find infringement even if they rejected Masimo’s patient-monitor interpretation. Under the doctrine of equivalents, he said, the Apple Watch could still infringe if it performs substantially the same function in the same way.

Masimo’s expert, engineer Vijay Madisetti, testified that Apple’s watch measures and records heart-rate data in a manner indistinguishable from Masimo’s patented method — and that the 10-minute stationary trigger is irrelevant because different patient monitors specialize in different events.

He likened Apple’s argument to dismissing a sleep-apnea monitor because it doesn’t work when someone is awake.

The Lawyers Behind the Battle

Masimo is represented by teams from Knobbe Martens and Sullivan & Cromwell.
Apple is backed by attorneys from WilmerHale, Gibson Dunn, and Haynes Boone.

With more verdicts pending and multiple appeals underway, Friday’s Apple $634M Verdict may mark only another turn in a legal war that shows no signs of slowing.