What is the test for admitting or denying evidence in a civil case?

^3. Both counsel sought to admit this evidence. However, neither argued that the failure to admit the evidence amounted to a violation of the confrontation clause or deprived appellants of an opportunity to present a complete defense, federal grounds which were therefore forfeited. (People v. Daniels (2009) 176 Cal.App.4th 304, 320, fn. 10 ["An appellate contention that the erroneous admission or exclusion of evidence violated a constitutional right is not preserved in the absence of an objection on that ground below"].)