Least privilege for PII data is not optional. It is the first control to reduce exposure when systems fail. Personally identifiable information only belongs in front of the people or processes that absolutely need it. Anything else is attack surface.
Apply least privilege at every layer. Lock down database roles so read access to PII fields is restricted by default. Segment services; a process that handles shipping addresses should not see national ID numbers. Enforce fine-grained access controls in code, backed by audited permission checks.
Review privileges often. Stale accounts and unused service keys are common. If a developer no longer needs production PII, revoke immediately. Automate privilege audits and integrate them into deployment pipelines. Logging should record every PII access, with alerts for patterns outside the norm.