Betrayal of confidence in the Court of Appeal.

In overturning Latham J's judgment in R v Department of Health, Ex Parte Source Informatics Ltd. that anonymisation does not obviate breaching a personal confidence, the Court of Appeal holds that where the duty of confidence arises in equity it does not prohibit the confidant using the confided information without the consent of the confider if this does not treat the confider unfairly (relative to the Court's view of the confider's legitimate interests). We argue that this principle--by bringing fairness to bear on the scope of the duty of confidence rather than on whether a breach of it may be lawful--has no authority in usable precedents; that the Court's interpretation of fairness in applying this principle is, in any event, incompatible with the Data Protection Act 1998 (in part because the Court has too narrow a conception of privacy); that the Court errs in holding that neither anonymisation of personal data nor use of anonymous data falls under the Data Protection Act; and that the Court's insensitivity to the vulnerability that leads patients to disclose information about themselves to health professionals for their treatment, leads it to misidentify the basis of the duty of confidence in such disclosures. The Court of Appeal's reasoning does not clarify the duty of confidence, but virtually abolishes it in the face of competing commercial and research interests.