Case Re-Opened: Masimo vs Apple Watch Patent Battle Rages On

A double-whammy of bad news for Apple today as Bloomberg reports that the blood-oxygen patent case between Apple and Masimo is to be reopened by the ITC, with Reuters adding that the tech giant must pay Masimo $634m for the original infringement.

This story has dragged on since 2020, so it’s good news that the ITC aims to conclude its latest investigation within six months.

How did we get here?

Masimo is a medical-monitoring technology company that owns patent No. 10,433,776 for light-based blood-oxygen (SpO2) measurement, widely referred to as pulse oximetry. Apple Watch’s latest generation of optical sensor was initially deemed to infringe the patent. Thus, in 2023, the ITC  banned the import of Apple Watch Series 9 and Ultra 2 as those, and newer models, used the sensor.

Apple then redesigned its software processing to get around the details of the patent. The same sensing still took place on the Watch, but it was processed on the iPhone – two pieces of hardware, purchased separately. This not-so-subtle difference convinced the Customs and Border Protection (CBP) that the redesigned watches no longer violated the original import ban.

Masimo was unhappy.

Masimo challenged the decision, arguing that the CBP had not provided sufficient notice and involvement in the decision, and that the CBP was not intended to resolve all patent infringement cases, especially complex and indirect cases like this. Furthermore, they argued that the new design still infringes the patent, as, despite the differences, it has an equivalent effect. Separately, Masimo is suing the CBP because of this.

The New ITC Review

The ITC appears to have listened to Masimo and has launched a review that is expected to conclude within six months. The review now also slightly widens the scope, covering these two areas.

1. The new review will decide the old issue. Namely, whether the original exclusion order should cover the redesigned Apple Watches and, hence, the ban reinstated
2. The ITC will also address whether Apple is inducing infringement. i.e. separately shipped products will still be paired and used in the US.

More fireworks

A California court has separately ruled on the same issues, finding that Apple must pay Masimo damages of $634m for the original infringement – a punishment, if you like. No doubt Apple will appeal this if there are grounds.

As noted previously, Masimo is suing the CBP, believing the latter to have overstepped its authority and remit.

Take Out

This old issue is edging closer to a resolution.

Where previously it looked like Apple’s financial clout and a clever redesign had put it in the clear. The balance seems to have swung closer to Masimo. The latter are surely going to receive substantial damages even if the $634m sum is lowered on appeal. Next, the ITC’s rapid investigation appears to be addressing precisely the issues of concern to Masimo and, at least superficially, seems to favour them.

In a broader note. This site expects an updated optical HR sensor from Apple in the 2026-27 timeframe. Almost certainly, this patent will have been designed out more elegantly within the sensor. If Apple can drag the legal proceedings out long enough, its watch sales will continue with the current tech until a new generation of sensors takes over.

The upside for apple is that its Watch sales continue uninterrupted in the USA, and it only has to deal with settling damages.

Sources:

• Reuters — jury verdict $634M and ITC new proceeding (Nov 14–15, 2025).
• Bloomberg Law — ITC review and CBP background.
• Masimo press release / ITC background (2023 exclusion order).
• Reuters / other reporting on Masimo’s lawsuit vs CBP.

Last Updated on 30 January 2026 by the5krunner

the5krunner

tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors.