Consent Propagation
Ensuring a consent decision reaches and is honoured by every system that processes the data, including those that received it before the decision changed.
Capturing consent is a form. Honouring it is a distributed systems problem: the decision has to reach every system that acts on the data, and withdrawal has to reach systems that already received it.
Four properties are needed. Granularity matching what was presented — a single "accept" that maps to six different processing purposes cannot demonstrate consent for any of them individually. Versioning, because consent is to a specific statement at a specific time, and both the statement and the timestamp are the evidence. Propagation to every downstream consumer, ideally as a consent event each subscribes to rather than a table each is trusted to check. Withdrawal handled as a first-class operation, which is the part most often missing: systems are built to receive an opt-in and have no path for the reversal.
The failure mode that produces regulatory attention is a withdrawal recorded centrally while a downstream marketing platform, which received the record months earlier, continues to process. The person experiences no change and complains, and the organisation's own consent database says everything is correct.