Even when EPD fails — when a design flaw or quality failure occurs in the presence of witnesses who understand what they are seeing — organizational structure ensures that accountability cannot flow from those who know to those with authority to act.
The Engineered Plausible Deniability series established that regulated entities design their own information systems to prevent adverse findings from entering the formal record. But EPD is not perfect — contamination events have witnesses, design flaws have engineers who know what they built, and quality failures eventually produce physical evidence. The Accountability Firewall is what makes EPD durable when EPD itself fails.
Organizational siloing, career incentive structures, legal constraints on disclosure, and institutional culture together form a firewall that contains knowledge of harm within organizational units whose knowledge does not create legal obligations for the institution as a whole. The Quality Assurance team knows. The Knowledge Firewall ensures that what the QA team knows never formally reaches the executive with authority to act, and that the engineer who raised the concern is structurally prevented from acting on it effectively.
This series documents the firewall's four structural components — the Liability Partition, the Treading Lightly Problem, the Omertà Structure, and the Collapse Conditions — and specifies what dismantling it would require.