Masimo, a medical-device maker, has filed a complaint against the US Customs and Border Protection (CBP) in the US District Court for the District of Columbia. The complaint alleges that the CBP exceeded its authority in an internal advice ruling on August 1, which overturned a January decision without notice or input from Masimo. The ruling allowed Apple to import watches with a blood oxygen feature that Masimo claims infringes on its patents. Apple's workaround involves computing and displaying the results on a paired iPhone, rather than on the watch itself. The CBP's investigation centered around whether Masimo's patents were "limiting," meaning they cover a device that reads, computes, and displays blood oxygen levels non-invasively. The International Trade Commission (ITC) had previously found that Masimo's patents were limiting, which led to an import ban on Apple Watches. Masimo's complaint suggests that the CBP's ruling may have been influenced by Apple's investments in US manufacturing, which were announced during the Trump administration. However, the investigation took place during the Biden administration, and the ruling was based on the ITC's interpretation of Masimo's patents. The ITC found that Masimo's patents only cover user-worn devices that read, compute, and display blood oxygen levels non-invasively, which Apple's redesigned feature no longer does. Masimo is bringing claims under the Administrative Procedure Act and the Fifth Amendment's due process clause.