Keep me logged in until I sign out. Evidentiary privileges are rights held by certain persons that allow them either to refuse to provide evidence or to prevent evidence from being offered against them. Privileges are contrary to the general rules that all relevant and competent evidence is admissible and that every citizen has an obligation to give evidence in a judicial proceeding.
Privileges also hinder the basic function of the judicial system, which is the search for truth.
Accordingly, privileges only exist to serve important interests and relationships, they are construed narrowly, and new ones are rarely created, at least by the courts. Since privileges are meant to vindicate a private or public interest in confidentiality, and since they are disfavored, they can be waived by the persons or entities they are meant to protect. Where more than one person holds a privilege, sometimes the act of only one is required to waive it and sometimes an act of both is required. In many cases, the nonholder who is a party to a privileged communication is required to assert the privilege on behalf of the holder. In California, no adverse inference may be drawn from the exercise of a privilege in any kind of case.