Q: How can Plaintiff shift to the defendant burden to prove they did not disclose the information? What statute defines?

A: In California, the burden of proof can be shifted to the defendant to prove they did not wrongfully disclose the plaintiff's information through a legal doctrine known as "res ipsa loquitur" ("the thing speaks for itself"). This doctrine applies when the incident would not typically occur without negligence, the evidence rules out the plaintiff's own actions as a cause, and the defendant had exclusive control over the instrumentality that caused the incident.

California Evidence Code section 646 codifies res ipsa loquitur. It states:

"(a) As used in this section, "defendant" includes any party against whom the res ipsa loquitur presumption operates.

(b) The judicial doctrine of res ipsa loquitur is a presumption affecting the burden of producing evidence.

(c) If the evidence, or facts otherwise established, would support a res ipsa loquitur presumption and the defendant has introduced evidence which would support a finding that he was not negligent or that any negligence on his part was not a proximate cause of the occurrence, the court may, and upon request shall, instruct the jury to the effect that:

(1) If the jury believes that the defendant was negligent and that his negligence was a substantial factor in bringing about the occurrence, the jury shall presume that the proximate cause of the occurrence was some negligent conduct on the part of the defendant; and

(2) The jury shall not find that the defendant's negligence was a substantial factor in bringing about the occurrence unless the jury believes, from all the evidence, that it is more probable than not that the occurrence was caused by some negligent conduct on the part of the defendant."

So in a case involving unauthorized disclosure of records, if the plaintiff can show:

1) Such disclosure would not ordinarily happen without negligence,

2) The records were in the exclusive control of the defendant, and

3) The plaintiff did not contribute to the unauthorized disclosure,

Then under Evidence Code 646, the burden shifts to the defendant to prove they were not negligent in allowing the disclosure to occur. The defendant must provide evidence showing it is more likely than not that the disclosure did not result from their negligence.

So in summary, California Evidence Code section 646 allows a plaintiff to use res ipsa loquitur to create a rebuttable presumption of the defendant's negligence in certain cases, shifting the burden to the defendant to prove they were not negligent. The unauthorized disclosure of confidential records is a scenario where this doctrine could potentially apply.