Defense in depth

A security and reliability principle, applied here to data governance, in which multiple independent protective layers are stacked so that a single point of failure in any one layer does not by itself allow a violation to reach production; a producer-side contract and consumer-side validation together are an example.

The security principle, illustrated by the Section 3G password-reset example, of layering multiple, independent controls (structural, then guardrail, then human approval) so that a single failure at one layer does not by itself produce a harmful outcome.

Stacking multiple independent checks (input filtering, the model, rule-based output validation, human review) so no single failure passes straight through to a real-world consequence. The output-validation layer is the highest-leverage and most-skipped.

The engineering practice of stacking multiple, independent safeguards (prevention, detection, mitigation, and recovery layers) between a potential failure and harm, so that any one layer failing still leaves the others standing.

Layering multiple, independent controls around a sensitive asset so that the failure of any single control does not leave the asset fully exposed. The direct response to single point of failure findings like the UnMarker watermark stripping research, which showed one control alone, however sophisticated, can fail.