Cal. Pen. Code § 911
The following oath shall be taken by each member of the grand jury: "I do solemnly swear (affirm) that I will support the Constitution of the United States and of the State of California, and all laws made pursuant to and in conformity therewith, will diligently inquire into, and true presentment make, of all public offenses against the people of this state, committed or triable within this county, of which the grand jury shall have or can obtain legal evidence. Further, I will not disclose any evidence brought before the grand jury, nor anything which I or any other grand juror may say, nor the manner in which I or any other grand juror may have voted on any matter before the grand jury. I will keep the charge that will be given to me by the court."
Ca. Pen. Code § 911