California, unlike other states, has codified the attorney-client (and other evidentiary) privileges.  Cal. Evid. Code §§ 900 et seq.  In an opinion issued last week, the California Court of Appeal provided a nice summary of how a court must assess attorney-client privilege claims:

A court, however, may not review the contents of a communication to determine whether the attorney-client privilege protects that communication. The attorney-client privilege is an absolute privilege that prevents disclosure, no matter how necessary or relevant to the lawsuit. The privilege attaches to all confidential communications between an attorney and a client regardless of whether the information communicated is in fact privileged. Accordingly, it is neither necessary nor appropriate to review a communication to determine whether the attorney-client privilege protects it.

Once the proponent makes a prima facie showing of a confidential attorney-client communication, it is presumed the communication is privileged and the burden shifts to the opponent to establish waiver, an exception, or that the privilege does not for some other reason apply. The opponent may not rely on the communication's content to make that showing.

Dp Pham, LLC v. Cheadle, 2016 Cal. App. LEXIS 288, 1-2 (Cal. App. 4th Dist. Apr. 15, 2016).

In Camera Review

The trial court in conducted an in camera review of the communications between the attorney and his client to determine whether they were privileged.  The Court of Appeal found this to be impermissible.   Presumably, the judge reviewed the communications in his chambers.  The word "camera" is a word derived from the Greek (καμάρα) and Latin (camera) meaning a vaulted room.  A camera obscura, which literally means a dark room, refers to a device using a black box used for projecting images.  The camera obscura eventually led to the modern camera.  The word "photography" is derived from two Greek words meaning light writing.