The Apple Watch's blood oxygen sensor has been at the center of what feels like a never-ending tennis match of legal back-and-forth.

In 2020, the Apple Watch Series 6 launched with the sensor that measures your blood's oxygen saturation (SpO2), which is how much oxygen red blood cells pick up from your lungs and transport to the rest of your body. That same year, global medical technology company Masimo filed a lawsuit claiming that Apple's sensor infringed its patents. In 2023, the US International Trade Commission sided with Masimo and imposed an import ban on Apple Watch Series 9 and Ultra 2 models.

However, on Friday, the ITC declined Masimo's request for another import ban on the Apple Watch and said it wouldn't review a preliminary ruling finding that the redesigned Apple Watch doesn't infringe Masimo's patents. This is a major win for Apple. 

Unless Masimo decides to appeal the decision, Apple can bring blood oxygen monitoring back to its devices. 

But based on the history of this case, it may not be the end of this match. 

The history of Apple's blood oxygen ban

The ITC became involved in the Masimo and Apple legal battle in 2021, and in January 2023, it upheld that Apple violated Masimo's patents. Then, in December 2023, the ITC banned Apple from importing its watches, including the Series 9 and Ultra 2, into the US. 

To avoid the ban, Apple disabled blood oxygen sensing on its devices. 

Ahead of the Apple Watch Series 11 launch, Apple reintroduced blood oxygen sensing in August 2025, which was approved by the US Customs and Border Protection. It got around the ban by using a paired iPhone to display blood oxygen levels instead of the Apple Watch. Masimo sued US Customs over this decision. 

In November 2025, a jury for the US District Court for the Central District of California found that Apple infringed one of Masimo's patents and awarded the company $634 million in damages. Apple told AppleInsider that it plans to appeal, claiming that the patent expired in 2022.

Though the ITC has rejected another ban on Apple's blood oxygen feature and declined Masimo's request to review the ruling in Apple's favor, Masimo may continue the battle, especially given its November win, after which the company released a statement saying, "We remain committed to defending our IP [intellectual property] rights moving forward."

An Apple representative didn't immediately respond to a request for comment. Masimo declined to comment.

In the meantime, if your curiosity gets the best of you, you could always purchase a pulse oximeter. It's a device that estimates your blood oxygen level by measuring the light that passes through your finger. No messy legal battles involved.