Cal. Const. art. I § 16
Trial by jury is an inviolate right and shall be secured to all, but in a civil cause three-fourths of the jury may render a verdict. A jury may be waived in a criminal cause by the consent of both parties expressed in open court by the defendant and the defendant's counsel. In a civil cause a jury may be waived by the consent of the parties expressed as prescribed by statute.
In civil causes the jury shall consist of 12 persons or a lesser number agreed on by the parties in open court. In civil causes other than causes within the appellate jurisdiction of the court of appeal the Legislature may provide that the jury shall consist of eight persons or a lesser number agreed on by the parties in open court.
In criminal actions in which a felony is charged, the jury shall consist of 12 persons. In criminal actions in which a misdemeanor is charged, the jury shall consist of 12 persons or a lesser number agreed on by the parties in open court.
Cal. Const. art. I § 16