On February 19, 2026, the UK Court of Appeal handed down its decision in DSG Retail Limited v The Information Commissioner [2026] EWCA Civ 140. The Court ruled that a controller’s data security duty applies to all personal data for which it acts as controller – irrespective of whether the information would constitute personal data in the hands of a third party (in this case, an attacker). Note that the case is concerned with events before the GDPR came into force, so the legal context is provided by UK Data Protection Act 1998 (“DPA 1998”), although the Court did take into account more recent jurisprudence, including CJEU case law.

The case adds useful colour to ongoing debates surrounding the definition of “personal data.” The Court of Appeal confirmed that a controller’s duty to implement appropriate measures to protect personal data applies to data that is “personal” from the perspective of the controller —even if a third-party attacker could not identify individuals from the exfiltrated dataset. This dovetails with the SRB v EDPS’s clarification that whether data is “personal” can depend on the context, while a controller’s obligations (such as transparency) must be assessed from the controller’s perspective at the relevant time (which, for the transparency principle, is at the time of collection of the data). (For more information on SRB v EDPS, see our prior post here.)