Masimo is taking the U.S. government to court over its decision to allow blood oxygen tracking to return to the Apple Watch, saying its decision was unlawful and that Apple’s workaround still infringes its sensor patents.
After an 18-month hiatus that followed a yearslong legal battle—as well as an import ban from the U.S. International Trade Commission (ITC)—Apple announced last week that pulse oximetry features would once again be available on certain models of its smartwatches.
According to the tech giant, instead of the sensor data being processed on the wrist, they would now be “measured and calculated” on the user’s iPhone—as Masimo held the patents on gathering readings from “user-worn devices.” Apple said it received the green light from U.S. Customs and Border Protection (CBP).
Now, Masimo is suing that department, in addition to Homeland Security Secretary Kristi Noem, saying CBP made the change unilaterally—and that it went back on a January 2024 finding that said Apple Watches could only be sold in the U.S. if they had the blood oxygen feature disabled.
“It has now come to light that CBP thereafter reversed itself without any meaningful justification, without any material change in circumstances, and without any notice to Masimo, let alone an opportunity for Masimo to be heard,” the company said in its complaint, filed yesterday in the federal district court of Washington, D.C.
“Specifically, on August 1, 2025, CBP issued an ex parte ruling permitting Apple to import devices that, when used with iPhones already in the United States, perform the same functionality that the ITC found to infringe Masimo’s patents,” it wrote. “Masimo only discovered this ruling on Thursday, August 14, 2025, when Apple publicly announced it would be reintroducing the pulse oximetry functionality through a software update.”
Masimo said the move deprived it of its rights to due process and that the agency exceeded its authority by nullifying the directives from the ITC. “CBP’s function is to enforce ITC exclusion orders, not to create loopholes that render them ineffective,” the company added.
It also noted that it only received a redacted copy of the CBP ruling from Apple after its lawyers sent a cease and desist letter. Masimo said its inquiries to the CBP resulted in a “terse” response stating that the document would be made available within 10 business days and that the decision to allow Apple Watches through was made under “exceptional circumstances,” but did not offer additional details.
Without making any accusations, Masimo's lawyers did take time to highlight Apple's commitments this year to invest hundreds of billions of dollars in U.S. manufacturing.
The CBP’s redacted Aug. 1 ruling has since been posted to the department’s database. The document said that when the newly redesigned Apple Watches are considered alone—as they were submitted to CBP in an import shipment of five watches that did not contain any iPhones—the agency does not consider them to directly infringe Masimo’s patents.
Masimo contended that shipping watches and smartphones into the U.S. separately should not be allowed, because it’s clear they’re meant to be paired together by the customer.
“Apple’s ‘redesign’ appeared to be a superficial modification expressly intended to circumvent the ITC’s exclusion order; the redesigned watches contained the same infringing components and retained (at the very least) capacity to perform the same infringing steps, except Apple offloaded one of those steps to the iPhone,” Masimo wrote in its complaint. The company is seeking a preliminary injunction to halt the CBP's ruling.
Apple previously appealed the ITC’s original decision in federal court, with oral arguments held in July.