California law provides that certain communications between a client and an attorney are privileged, and disclosure of that confidential communication cannot be compelled. (Evidence Code §§952 & 954) The confidential information must be transmitted between the client and the attorney in the course of that professional relationship, in confidence by which no third persons, other than those necessary to further the interest of the client (e.g. a translator), are present.
The California Supreme Court held in Costco Wholesale Corporation vs. Superior Court (2009) that a report given by an attorney to his client, Costco, on the result of conducting an investigation into employment matters, including the results of interviews conducted with managers of the client, was protected by the attorney-client privilege even though the legal opinion contained the results of interviews with company managers and were not strictly the legal opinions of the attorney. The employees in a class-action lawsuit sought to compel production of the attorney’s opinion letter to the employer. The Supreme Court held that the attorney-client privilege attached to the attorney’s opinion letter in its entirety, because the employer had retained the attorney to provide legal advice, and held the privilege applied even though the communication included unprivileged material, such as the statements made by managers.
In summary, a client seeking the advice of an attorney on a legal matter, who wishes the communication be kept strictly secrete and confidential, should assure that the communications are made in the course of the attorney-client relationship for the purpose of obtaining legal advice and without the presence of any third party, such as a friend or business associate.
An attorney-client relationship is not created between the client and the law firm until the attorney and client execute a written retainer agreement describing the legal work to be performed.