A decision line is the boundary that defines what an AI system may do on its own, what it may recommend, and what must stay with a human operator. In cyber security, this matters because an AI can be accurate and still be unsafe if it is allowed to take high-impact actions without review.
Security teams use decision lines to control automation in tools like SIEM, SOAR, and EDR. A model might rank alerts, suggest a phishing verdict, or recommend containment steps, while a person approves account lockouts, endpoint isolation, firewall changes, or key rotation. That separation reduces the risk of false positives, bad model output, and over-automation during an incident. Attackers can also target weak decision lines by feeding misleading data or prompt injection into systems that trust AI output too much. A clear decision line keeps the model useful for speed and analysis, while preserving human authority for sensitive security actions.