Court Increases Apple’s Patent Liability in Masimo Dispute

Apple’s use of a low-power pulse-oximetry method in its Watch models was challenged by medical-technology firm Masimo. An International Trade Commission ruling in 2023 required Apple to disable the blood-oxygen sensor on two Watch models to permit U.S. sales, prompting a redesign that was re-introduced in 2025. Separately, a 2025 jury found that Apple Watch features—including heart-rate notifications— infringed Masimo’s pulse-oximetry patent, awarding $634 million in damages. The patent had expired in June 2022, so the judgment applies only to earlier sales and does not affect current Watch functionality.

MacRumors

A federal judge has now ordered Apple to pay an additional $184 million in interest on the original $634 million judgment, raising the total liability to roughly $818 million. Masimo had sought a 7 percent rate, which would have produced a $243 million interest bill; instead, the judge applied Masimo’s own borrowing rate, compounded annually from the start of the infringement period. The ruling notes that post-judgment interest will continue to accrue until Apple satisfies the judgment.

MacRumors

Judge James V. Selna emphasized that the interest calculation should reflect the cost to Masimo of being deprived of royalty payments during the infringement period. By using the plaintiff’s borrowing rate rather than the higher statutory rate requested, the court aimed to balance compensation with fairness, while still ensuring Masimo is made whole for the period it was denied royalties.

MacRumors

Apple must now address the enlarged financial obligation while continuing to comply with the earlier ITC-mandated redesign of its blood-oxygen feature. The accruing post-judgment interest means the total amount due will increase until the company pays the judgment in full, extending the financial impact of the dispute beyond the initial $634 million award.

9to5Mac