What is the test for defaming a witness in a civil proceeding?

[146 Cal.App.3d 234] Second, in Thornton the court formulated the following test: "This approach, which ignores legal niceties and merely looks to some logical connection between the utterance and the proceeding, solves most problems. On the one hand it does not protect attorneys, witnesses and litigants who use the mere fact that they are talking in the course of a judicial proceedings as a pretext to defame persons with respect to matters which have nothing whatever to do with the question under consideration, yet it does shield counsel, his client and witnesses from having their motives questioned and being subjected to litigation if some connection between the utterance and the judicial inquiry can be established." (Thornton v. Rhodes, supra, 245 Cal.App.2d 80, 90, 53 Cal.Rptr. 706, fn. omitted.)