A conflict of interest happens when one role is expected to judge, monitor, or challenge a decision, but also has duties that benefit from that same decision. In cyber security, this matters because control functions must stay independent. If the same person builds a system, approves its risk, and later audits it, their oversight can become biased or too lenient.
This problem appears in privacy, AI governance, and security operations. A Data Protection Officer, for example, should advise and monitor rather than own deployments. The same principle applies to security teams: the person who sets access policy should not be the only person verifying whether that policy works. Strong defenses separate operational ownership from review, so incident handling, risk acceptance, and compliance checks remain trustworthy and traceable.