Cal. CCP § 1991

Disobedience to a subpoena, or a refusal to be sworn, or to answer as a witness, or to subscribe an affidavit or deposition when required, may be punished as a contempt by the court issuing the subpoena.

When the subpoena, in any such case, requires the attendance of the witness before an officer or commissioner out of court, it is the duty of the officer or commissioner to report any disobedience or refusal to be sworn or to answer a question or to subscribe an affidavit or deposition when required, to the court issuing the subpoena. The witness shall not be punished for any refusal to be sworn or to answer a question or to subscribe an affidavit or deposition, unless, after a hearing upon notice, the court orders the witness to be sworn, or to so answer or subscribe and then only for disobedience to the order.

Any judge, justice, or other officer mentioned in subdivision (c) of Section 1986, may report any disobedience or refusal to be sworn or to answer a question or to subscribe an affidavit or deposition when required to the superior court of the county in which attendance was required; and the court thereupon has power, upon notice, to order the witness to perform the omitted act, and any refusal or neglect to comply with the order may be punished as a contempt of court.

In lieu of the reporting of the refusal as hereinabove provided, the party seeking to obtain the deposition or to have the deposition or affidavit signed, at the time of the refusal may request the officer or commissioner to notify the witness that at a time stated, not less than five days nor more than 20 days from the date of the refusal, he or she will report the refusal of the witness to the court and that the party will, at that time, or as soon thereafter as he or she may be heard, apply to the court for an order directing the witness to be sworn, or to answer as a witness, or subscribe the deposition or affidavit, as the case may be, and that the witness is required to attend that session of the court.

The officer or commissioner shall enter in the record of the proceedings an exact transcription of the request made of him or her that he or she notify the witness that the party will apply for an order directing the witness to be sworn or to answer as a witness or subscribe the deposition or affidavit, and of his or her notice to the witness, and the transcription shall be attached to his or her report to the court of the refusal of the witness. The report shall be filed by the officer with the clerk of the court issuing the subpoena, and the witness shall attend that session of the court, and for failure or refusal to do so may be punished for contempt.

At the time so specified by the officer, or at a subsequent time to which the court may have continued the matter, if the officer has theretofore filed a report showing the refusal of the witness, the court shall hear the matter, and without further notice to the witness, may order the witness to be sworn or to answer as a witness or subscribe the deposition or affidavit, as the case may be, and may in the order specify the time and place at which compliance shall be made or to which the taking of the deposition is continued. Thereafter if the witness refuses to comply with the order he or she may be punished for contempt.