Apple Watch Series 9 models are displayed amongst other new products during a launch event at Apple Park in Cupertino, California, on Sept 12, 2023. (PHOTO / AFP)

Apple urged a US appeals court on Friday to overturn a US trade tribunal's decision to ban imports of some Apple Watches in a patent dispute with medical-monitoring technology company Masimo.

Apple told the US Court of Appeals for the Federal Circuit that the US International Trade Commission's decision was based on a "series of substantively defective patent rulings", and that Masimo failed to show it had invested in making competing US products that would justify the order.

Representatives for Apple and Masimo did not immediately respond to requests for comment on the filing.

The appeals court reinstated a ban in January, leading Apple to remove pulse oximetry capabilities from watches sold during the appeal

Irvine, California-based Masimo has accused Apple of hiring away its employees and stealing its pulse oximetry technology after discussing a potential collaboration. Apple first introduced pulse oximetry to its Series 6 Apple Watches in 2020.

Masimo convinced the ITC on Dec 26 to block imports of Apple's latest-edition Series 9 and Ultra 2 smartwatches after finding that their technology for reading blood-oxygen levels infringed Masimo's patents.

Apple temporarily resumed sales of the watches the next day after persuading the Federal Circuit to pause the ban. The appeals court reinstated the ban in January, leading Apple to remove pulse oximetry capabilities from watches sold during the appeal, which Apple has said could last at least a year.

US Customs and Border Protection separately determined in January that redesigned versions of the watches did not violate Masimo's rights and would not be not subject to the ban. Masimo said in a court filing that the watches "definitively do not contain pulse oximetry functionality."

Apple told the Federal Circuit on Friday that the ban could not stand because a Masimo wearable covered by the patents was "purely hypothetical" when it filed its ITC complaint in 2021.

The tech giant also argued that Masimo's patents were invalid and that its watches did not infringe them.