Is an evidentiary privilege recognized to be a special defense under Code of Civil Procedure?

The parties have cited no case, nor have we found one through our own research, wherein an evidentiary privilege was recognized to be a special defense under Code of Civil Procedure section 597. While defendants cite to dicta in the case of Mayes v. Sturdy Northern Sales, Inc. (1979) 91 Cal.App.3d 69, 79, 154 Cal.Rptr. 43, the passage that "privilege is an affirmative defense that must be pleaded and proved," does not refer to evidentiary privileges. It refers to the "privilege of one who has a financial interest in the business of another" (id., at p. 78, 154 Cal.Rptr. 43) in the context of tort liability for intentional interference with a contract.

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