The medical technology firm Masimo has initiated a lawsuit against US Customs and Border Protection (CBP) as a means to challenge the agency’s recent decision permitting Apple to reinstate the blood oxygen tracking functionality on Apple Watches.

Since 2020, Apple has been entangled in legal battles regarding Masimo’s patent for blood oxygen sensors, having to deactivate the feature on US Apple Watch models due to an ITC import ban implemented in December 2023. Masimo, in a grievance submitted on Wednesday, alleged that the CBP did not notify the company about reversing the International Trade Commission’s restrictions, thus precluding Masimo from reviewing or contesting the ruling. Masimo only became aware of the reversal after Apple unveiled its “redesigned” pulse oximetry function last week, which now measures blood oxygen levels using iPhones instead of the Apple Watch.

Although no direct claims were stated, Masimo highlighted in the document that Apple has made “a series of substantial investments in the United States” after its efforts to overturn the ITC ban proved unsuccessful. Masimo pointed out that despite ongoing patent infringements, the CBP permitted Apple to reactivate the feature, asserting 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 claimed in a supporting statement reported by Bloomberg Law.

Masimo is requesting a temporary restraining order and preliminary injunction to counteract the new ruling allowing Apple to reintegrate the blood oxygen features, aiming to reestablish the original ruling that stipulated Apple could only import Watches to the US if the infringing technology was entirely dismantled.