The case adds a new twist to a years-long patent battle that has already triggered an import ban, a redesign, and dueling lawsuits, with both companies still awaiting a key appeals court ruling.
Medical monitoring technology company Masimo sued U.S. Customs and Border Protection on Wednesday, accusing the agency of improperly allowing Apple to import smartwatches with blood-oxygen reading technology despite an International Trade Commission (ITC) ban.
Masimo told a federal court in Washington, D.C., that Customs reversed its prior determination without notice, enabling Apple to resume importing devices equipped with pulse oximetry, Reuters reported.
The company said it only learned of the Aug. 1 decision when Apple announced last week that it would reintroduce blood-oxygen features on its Series 9 and Ultra 2 watches.
Masimo argued the move deprived it of due process and asked the court to block Customs’ decision, saying the agency’s role is to enforce ITC exclusion orders, not “create loopholes that render them ineffective.”
The lawsuit marks the latest turn in a bitter legal fight dating back years. In 2023, ITC determined Apple infringed Masimo patents on its blood-oxygen technology, resulting in an import ban on Apple’s Series 9 and Ultra 2 models.
Apple temporarily suspended U.S. sales in December 2023, and the U.S. Court of Appeals for the Federal Circuit later stayed the import ban and lifted its sales suspension.
In January 2024, Masimo revealed in a court filing that Customs had cleared Apple to sell redesigned watches said to omit the contested technology. However, Apple did not publicly detail the changes.
Apple argued at the time that the redesign removed pulse oximetry entirely, while Masimo maintained the approval undermined Apple’s claim that a reinstated ban would cause irreparable harm.
The Federal Circuit is still considering Apple’s appeal, a process the company has said could take at least a year.
Apple has included a blood-oxygen sensor since its Series 6 Watch in 2020. Masimo has accused the tech giant of hiring away employees and stealing its technology after failed collaboration talks, and has separately sued for patent infringement and trade secret theft.
Apple countersued, calling Masimo’s claims an effort to clear a path for its competing W1 health watch launched in 2022.
On Stocktwits, retail sentiment toward Masimo was reported as ‘bullish’ with ‘normal’ message volume, while sentiment toward Apple was ‘extremely bearish’ on ‘extremely low’ activity.
Masimo’s stock has declined nearly 12% so far in 2025, while Apple’s stock fell 9.4% over the same period.
For updates and corrections, email newsroom[at]stocktwits[dot]com.<