A federal appeals court ruled that Apple Watches with a blood oxygen measurement feature cannot be imported, as the iPhone maker battles out a patent dispute.

Medical technology company Masimo has accused Apple of stealing its pulse oximetry technology and hiring away its employees.

Apple shares were down half a percent after the U.S. Court of Appeals for the Federal Circuit ruled the company can no longer sell the Series 9 and Ultra 2 Apple Watches.

The affected watches cannot be imported starting at 5 p.m. on Jan. 18 while Apple appeals a December decision by the U.S. International Trade Commission to halt imports of the devices.

The legal fight could take a year and analysts expect Apple to disable the disputed feature in the meantime to comply with the ban and keep the watch on sale.

Apple has included a pulse oximeter feature in smartwatches since its Series 6 Apple Watch in 2020.

It has countersued Masimo for patent infringement, calling Masimo's legal actions a "maneuver to clear a path" for its own competing watch.

An Apple company report said its wearables, home and accessory business, which includes the Apple Watch, AirPods and other products, brought in $8.28 billion in revenue during the third quarter of 2023.

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