Episode 18: Three Lines of Defense Model
Welcome to The Bare Metal Cyber CRISC Prepcast. This series helps you prepare for the exam with focused explanations and practical context.
Imagine a building designed to withstand risk. At the base, you have the people doing the work. Above them, the team making sure work is done safely. And at the top, an independent observer checking whether anything is being missed. This is the essence of the Three Lines of Defense model—a governance framework designed to clearly assign risk responsibilities. The First Line is business and operations. These are the risk takers and owners. The Second Line provides oversight through risk managers, compliance functions, and legal teams. The Third Line is assurance—internal audit and independent evaluators. This structure promotes segregation of duties, transparency in operations, and accountability in decision-making. The CRISC framework uses this model to test whether you know not just what needs to be done, but who should do it—and just as importantly, who should not. The Three Lines model is not just a theory. It is a practical guide for organizing risk ownership in every process, every decision, and every control.
At the ground floor of the risk accountability structure sits the First Line of Defense. This is where risk is executed. These are the teams running the day-to-day business processes, systems, and workflows. They don’t just witness risk—they interact with it directly. The First Line owns and manages risk through their activities and decisions. They are responsible for implementing controls, maintaining them, and reporting issues when they arise. Roles in this line include IT operations, human resources, finance, customer service, and manufacturing—any function that delivers services, handles assets, or engages with customers. On the exam, questions about initiating action, performing tasks, or applying controls are typically rooted in First Line responsibility. A scenario that involves a missed step in payroll processing or a change made without approval usually points to the First Line. The key is this: the First Line does the work. They own the outcome and manage risk through execution, not oversight.
The Second Line of Defense exists to guide and oversee. This line includes risk managers, compliance officers, legal counsel, and other governance roles that support the First Line. These individuals do not operate business processes directly, but they shape how risk is managed. The Second Line monitors, challenges, and supports the First Line. They develop policies, recommend controls, perform risk assessments, and ensure adherence to laws, regulations, and internal frameworks. Importantly, the Second Line is not independent in the same way the Third Line is—but it must remain separate from day-to-day operations. On the CRISC exam, answers that involve creating policy, conducting a compliance review, or advising on regulatory risk typically belong to the Second Line. A common mistake is to assign execution to this group. Remember, the Second Line does not operate the controls—it ensures the controls are well designed and properly supported. Their job is to enable the First Line to perform risk duties effectively.
The Third Line of Defense is all about independence. Internal audit and other truly independent evaluators occupy this space. Their mission is to provide assurance that risk management practices and internal controls are working as intended. They do not design controls. They do not execute tasks. They assess whether controls exist, whether they function, and whether governance is being followed. The Third Line typically reports directly to the board of directors or the audit committee to preserve objectivity and avoid influence from operations or oversight functions. On the exam, look for questions that mention audit findings, effectiveness reviews, or independent assessments. These scenarios belong to the Third Line. If a control failure was discovered during an internal audit, that is a Third Line discovery. Their distance from execution gives credibility to their evaluations. CRISC expects you to recognize this independence and to respect the boundaries that make assurance functions trustworthy.
The benefits of the Three Lines model are numerous, and they begin with clarity. This framework clearly separates responsibility, preventing conflicts of interest. It ensures that those who perform work are not the ones assessing their own performance. It provides objective oversight and strengthens transparency. Assurance functions remain credible because they are not involved in execution or oversight. This model also gives boards better visibility into how risks are handled. They can rely on the Third Line to confirm that the Second Line is guiding the First Line correctly. The result is a stronger control environment and more confident decision-making at the highest level. CRISC recognizes this model as a maturity marker. When used effectively, the Three Lines structure elevates governance from reactive firefighting to proactive, strategiCRISC leadership. On the exam, well-structured scenarios reflect this model with clear role boundaries and predictable escalation paths. Fragmented structures often point to the opposite—governance immaturity and increased exposure.
Even a good model can fail if roles blur or responsibilities overlap. One common mistake is the First Line designing or modifying controls without input from the Second Line. This may result in inconsistent or noncompliant risk handling. Another risk arises when the Second Line blurs into the First Line—when compliance teams begin executing rather than overseeing. This reduces independence and can lead to enforcement problems. The most serious failure occurs when the Third Line gets involved in control design. This destroys their objectivity and compromises the credibility of audits. The CRISC exam often tests your ability to assign responsibilities correctly. If a scenario presents a control failure, you’ll need to determine which line failed—and why. If an audit recommends a new policy, that is a misstep. That recommendation belongs to the Second Line. Choose answers that preserve role clarity, respect structural independence, and restore accountability where it has broken down.
Escalation is the communication lifeline that connects the Three Lines. Risk incidents, exceptions, and new threats must flow upward to ensure timely decisions and responses. The First Line reports issues as they occur. The Second Line ensures that reporting happens, analyzes trends, and ensures escalation follows procedure. The Third Line provides assurance that escalation is functioning. If an incident occurs and no one is informed, it is often the Second Line that failed. If a recurring risk isn’t addressed, the Third Line may have overlooked a systemic failure. Escalation failures can lead to regulatory breaches, reputational damage, or missed opportunities for strategic response. On the exam, watch for scenarios where escalation either prevented harm or failed to deliver a warning. Choose answers that ensure timely, structured, and documented communication between the lines. Risk cannot be managed in silence. Every line must communicate, and the structure must ensure those communications are heard and acted upon.
The Three Lines model must also align with enterprise strategy. The First Line is responsible for delivering operations in a way that supports strategic objectives. The Second Line ensures those operations comply with policy and that emerging risks are visible to leadership. The Third Line ensures both are functioning—providing assurance that the risk posture aligns with the board’s expectations. All three lines must operate within the organization’s defined risk appetite. When that alignment breaks, the signs are visible. You’ll see disconnected actions, redundant reporting, or conflicting risk decisions. On the exam, clues may include terms like “the risk report did not reflect current strategy” or “teams acted without understanding the enterprise’s goals.” These suggest misalignment. CRISC professionals are responsible not only for maintaining the lines of defense but for ensuring they support strategic clarity. Risk cannot be managed in isolation. It must always reflect what the organization values and how it plans to grow.
The Three Lines model continues to evolve. Traditional definitions focused on rigid separation of duties, but modern risk environments demand more collaboration. Organizations now encourage communication between the lines, especially when dealing with emerging threats, evolving technologies, or cross-functional projects. Boundaries still matter—but they are applied with flexibility. Technology, data analytics, and continuous monitoring are blurring lines in execution. For example, real-time dashboards may be used by all three lines for different purposes. CRISC candidates are expected to respect the structure but adapt to dynamic contexts. Frameworks like COSO ERM and the Institute of Internal Auditors’ 2020 update reflect this shift. They advocate for cooperation, agility, and shared responsibility—while preserving the need for independence in assurance. On the exam, you may be asked to choose between a rigid model and a collaborative one. The best answers balance structure with the need for adaptability.
Recognizing the Three Lines in CRISC exam questions is often about asking, “Who should act?” If a question begins with “Who is responsible for,” the answer must align with the proper line. If an issue was not detected, ask which line should have seen it. If a question asks who should review control effectiveness, that’s the Third Line. If a policy needs to be updated, that’s a Second Line responsibility. Each line has a purpose, and those purposes must not be confused. The best answers respect independence, avoid role conflicts, and clarify accountability. Misassigning responsibility is one of the most common ways candidates miss questions. Read carefully. Look for structural clues. Assign the task to the line with the right mandate. That’s how the model works—and that’s how you’ll pass the exam with confidence.
Thanks for joining us for this episode of The Bare Metal Cyber CRISC Prepcast. For more episodes, tools, and study support, visit us at Baremetalcyber.com.
