Medical tech company Masimo is suing US Customs and Border Protection (CBP) in an attempt to overturn the agency’s decision to allow Apple to restore the blood oxygen tracking feature on Apple Watches.

Apple has been embroiled in legal disputes over Masimo’s blood oxygen sensor patent since 2020, disabling the feature on supported US Apple Watch models following an ITC import ban in December 2023. In a complaint filed on Wednesday, Masimo said that the CBP failed to notify the company of its decision to reverse the International Trade Commission restrictions, leaving Masimo with no opportunity to review or challenge the ruling. Masimo said it only learned that the ban had been reversed after Apple announced its “redesigned” pulse oximetry feature last week, which now calculates blood oxygen levels on iPhones instead of the Watch.

While no direct accusations were made, Masimo called out in the filing that Apple has made “a series of substantial investments in the United States” after its appeals to overturn the ITC ban were denied. Masimo noted that the CBP then allowed Apple to reactivate the feature, despite the company continuing to infringe on Masimo’s patents, and that “whatever proceeding led to this new ruling departed substantially from CBP’s established practice regarding LEO ruling requests.”

“Each passing day that this unlawful ruling remains in effect irreparably deprives Masimo of its right to be free from unfair trade practices and to preserve its competitive standing in the US marketplace,” Masimo said in a supporting statement seen by Bloomberg Law.

Masimo is seeking a temporary restraining order and preliminary injunction to prevent the new ruling that allows Apple to restore blood oxygen features, and reinstate the original ruling that determined Apple could only import Watches to the US if the infringing patent tech had been completely disabled.