Apple Watch Blood Oxygen Returns, but Masimo Drags Apple Back to Court

The Apple Watch’s blood oxygen saga has taken yet another dramatic turn.

Medical tech company Masimo is suing U.S. Customs and Border Protection after the agency quietly greenlit Apple’s return of pulse oximetry features on its watches – despite an ongoing patent battle.

Masimo argues that Customs abruptly reversed a prior ban without proper notice, letting Apple reintroduce the feature via recent software updates. The twist? Blood oxygen readings are no longer processed on the watch itself. Instead, the data now flows to the paired iPhone, where results show up in the Health app under the Respiratory section. Apple says this complies with Customs’ revised approval terms.

The dispute began back in 2023 when the U.S. International Trade Commission sided with Masimo, blocking Apple from selling Series 9, Series 10, and Ultra 2 models with blood oxygen enabled. Apple dodged a sales freeze by shipping the hardware with the function disabled on U.S. units. That strategy kept shelves stocked while Apple searched for a workaround.

The workaround finally arrived in iOS 18.6.1 and watchOS 11.6.1. Users can once again measure oxygen saturation, but through a slightly more complicated route. Masimo, however, is furious – claiming Customs acted outside its authority and undermined patent protections. The company has asked a Washington court to overturn the decision and restore the exclusion order.

For Apple Watch owners, it’s welcome news that the tool is back, even if it requires a detour through the iPhone. But the courtroom battle shows no signs of slowing down, and the future of blood oxygen tracking on Apple’s wearables remains entangled in legal red tape.