What is the test for determining whether discrimination was a substantial motivating factor/reason for the adverse employment action?

determine "whether discrimination was 'a substantial motivating factor/reason'" for the adverse employment action].) "Substantial motivating reason" is explained in CACI No. 2507 as "a reason that actually contributed to the [discharge]. It must be more than a remote or trivial reason. It does not have to be the only reason motivating the [discharge]." These jury instructions demonstrate the application of the "substantial motivating reason" test to determine whether there is a causal link between the discharge and a violation of public policy generally is a question of fact. However, it is not uncommon for the employer's motivation to be decided as a matter of law at the summary judgment stage. (E.g. King v. United Parcel Service, Inc. (2007) 152 Cal.App.4th 426, 433-437 [summary judgment for employer affirmed; plaintiff failed to present substantial evidence of causal link between prohibited motivation and his discharge].)