Purpose limitation

Purpose limitation is the GDPR principle that personal data must be collected for specified, explicit and legitimate purposes and not further processed in a way incompatible with them.

Part of the Learn hub and the customer data glossary.

What it means in practice

Purpose limitation is one of the principles in GDPR Article 5(1)(b) 1. Further processing for archiving in the public interest, scientific or historical research, or statistical purposes is not treated as incompatible, subject to the safeguards in Article 89(1).

When a team wants a new use without fresh consent, Article 6(4) requires a compatibility test. The controller takes account, among other things, of the link between the purposes, the context of collection, the nature of the data (especially special categories), the possible consequences for individuals and the safeguards in place. The principle sits with accountability: the controller must be able to demonstrate compliance (Article 5(2)).

A customer data platform makes this hard because its value comes from reuse. If every team can query every attribute, purposes blur. The practical control is to tag data with the purposes it was collected for, record consent per purpose, and check the purpose at activation instead of relying on goodwill. Treat model training and AI-agent access as separate purposes to assess before they start.

Example (retail banking): a bank collects transaction data to run payment services. Using it to build marketing segments is a different purpose. It needs its own compatibility assessment or a separate basis such as consent, and the outcome should be documented.

US healthcare works differently. HIPAA limits uses and disclosures of protected health information to those it permits and requires authorisation for marketing uses, with narrow exceptions (45 CFR 164.508(a)(3)).

Related terms

• Data minimisation: the companion principle.
• Consent state: consent is tied to a purpose.
• Activation: where purpose is checked.
• Data processing agreement: fixes a processor's purposes.
• Audit ledger: evidence of compliance.

Where it matters

• Customer journey orchestration: reuse of data across journeys.
• Consent withdrawal across channels: honouring purpose-specific choices.

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