Apple Set for Billion-Dollar Trial in Clash Over Watch Secrets

A heated part of Apple Inc.’s sprawling legal dispute with a medical-devices maker over some functions and designs for the Apple Watch comes to a head this week as Masimo Corp. puts its trade-secrets theft case before a federal jury in California.

Masimo and co-plaintiff Cercacor Laboratories Inc., a Masimo spinoff that owns certain licensing rights to many Masimo patents, allege that Apple stole trade secrets, including some related to technology that uses light sensors to measure the amount of oxygen in the bloodstream.

They accused Apple of using confidential information from two former executives it hired, one from ...