California Code, Penal Code - PEN § 1054.7

The disclosures required under this chapter shall be made at least 30 days prior to the trial, unless good cause is shown why a disclosure should be denied, restricted, or deferred. If the material and information becomes known to, or comes into the possession of, a party within 30 days of trial, disclosure shall be made immediately, unless good cause is shown why a disclosure should be denied, restricted, or deferred. “Good cause” is limited to threats or possible danger to the safety of a victim or witness, possible loss or destruction of evidence, or possible compromise of other investigations by law enforcement.

Upon the request of any party, the court may permit a showing of good cause for the denial or regulation of disclosures, or any portion of that showing, to be made in camera. A verbatim record shall be made of any such proceeding. If the court enters an order granting relief following a showing in camera, the entire record of the showing shall be sealed and preserved in the records of the court, and shall be made available to an appellate court in the event of an appeal or writ. In its discretion, the trial court may after trial and conviction, unseal any previously sealed matter.