A US judge in California on Monday declared a mistrial in Masimo's smartwatch trade secret lawsuit against Apple after jurors failed to reach a unanimous verdict in the potential billion-dollar case.

A Masimo spokesperson said in a statement that the company was "disappointed that the jury was unable to reach a verdict" but intends to retry the case.

The jury in federal court in Santa Ana had been asked to determine whether Cupertino, California-based Apple misused confidential information from Masimo related to the use of light to measure biomarkers including heart rates and blood oxygen levels.

The jury began deliberating on April 26 after a trial lasting about three weeks before US District Judge James Selna.

Apple said in a statement that it "deeply respects intellectual property and innovation and does not take or use confidential information from other companies," and will ask the court to dismiss the remaining claims in the case.

Irvine, California-based Masimo and its spinoff Cercacor Laboratories Inc sued Apple in 2020, accusing it of stealing trade secrets and using them to create and sell several Apple Watch models.

The lawsuit claimed Masimo representatives met with Apple in 2013 about integrating its inventions into Apple products and that Apple subsequently hired away two executives - one from Masimo and one from Cercacor - and used their knowledge to copy the technology.

Masimo asked for more than $1.8 billion in damages, reduced from its initial request for $3.1 billion after the judge dismissed some of its trade-secret claims during trial.

Apple in a court filing called Masimo's lawsuit a "maneuver to clear a path" for its own smartwatch. Apple sued Masimo in Delaware last year, accusing it of patent infringement.

Smartwatches, mobile devices worn on the wrist with an array of capabilities, are a lucrative market, with global sales worth tens of billions of dollars.

Masimo has also sued Apple at the US International Trade Commission over Apple Watch imports that it said violated its patent rights. An ITC judge preliminarily ruled in favor of Masimo in January, which could lead to an import ban on infringing Apple Watches if the full commission affirms the decision.

Apple is facing another potential Apple Watch import ban in a separate patent fight with Mountain View, California-based medical device maker AliveCor over heart-monitoring technology. © Reuters