What is the test for determining whether privileged information is privileged in a civil case?

"When the right to disclosure clashes with a privilege, the court is required to 'indulge in a careful balancing' of the need for disclosure against the fundamental right of privacy. [Citation.] The scope of the privilege is determined by balancing the interests protected by shielding the evidence sought with those advanced by disclosure. [Citations.] When the balance swings in favor of disclosure, the court is required to limit the scope of discovery 'to the extent necessary for a fair resolution of the lawsuit.' [Citations.]" (Scull v. Superior Court, supra, 206 Cal.App.3d at pp. 790-791, 254 Cal.Rptr. 24.)