The trial court did not abuse its discretion in disqualifying the Gibson Dunn firm. Opposing party Hausman inadvertently disclosed to his sister-in-law a confidential email he had received from his personal attorney. The sister-in-law gave the email to Gibson Dunn’s client who gave it to the Gibson Dunn attorney. Gibson Dunn used the email in the litigation. Held, the State Comp. Ins. Fund v. WPS Inc. (1999) 70 Cal.App.4th 644 duty to disclose to the privilege holder that one has come into possession of apparently privileged documents arises no matter how the attorney receives the material. Whenever a reasonably competent attorney would conclude that the document is privileged and likely was inadvertently disclosed, the attorney must refrain from further examining the document and notify the privilege holder that the attorney has come into possession of the document. Even if the attorney thinks the privilege was waived or another exception to the privilege applies, he must refrain from further reviewing or disclosing the document unless and until the privilege holder has agreed or the court has ruled the document is not privileged. The trial court properly disqualified the attorney in this case since he used the privileged document without following the required State Comp. procedures. Disqualification was reasonably necessary because there was a reasonable likelihood otherwise that the attorney’s improper use of the email would affect the outcome of the case, the integrity of judicial proceedings and the public’s confidence in those proceedings.