Apple's Watch infringed a rival's blood-oxygen patent — the US banned it at the border

Masimo, a maker of hospital pulse-oximetry monitors, accused Apple of hiring away its engineers and building the Apple Watch's blood-oxygen sensor on patented light-based measuring technology it never licensed. On 26 October 2023 the US International Trade Commission ruled the Apple Watch Series 6 through 9 infringed two of Masimo's patents and ordered an import ban on the offending models, effective 26 December 2023.

Because the ban only stopped new units crossing the border, Apple could keep selling Watches already in the US — but it chose to pull the Series 9 and Ultra 2 preemptively, halting online sales on 21 December and in-store sales on 24 December, then shipped a software update that recalculated blood-oxygen readings differently to try to route around the injunction. A US Court of Appeals judge granted Apple a temporary stay days later, and sales resumed while the appeal proceeded.

The ITC case never awarded Masimo a cent — an import ban is not damages. That came separately: a 2023 trade-secret trial over the same underlying dispute ended in a hung jury after the judge capped potential damages at $1.85 billion, but a follow-on patent-infringement suit reached a federal jury in November 2025, which ordered Apple to pay Masimo $634 million for infringing its smartwatch patents. Apple said it disagreed and would appeal.