Quick Answer
The correct answer is the Clark-Wilson model. This model is the best fit because it enforces integrity through well-formed transactions and separation of duties, directly matching the requirement that doctors can write new records but cannot modify existing ones. It uses constrained data items (CDIs), transformation procedures (TPs), and integrity verification procedures (IVPs) to ensure that only authorized users perform specific operations, preventing unauthorized modifications. On the CISSP exam, this scenario tests your understanding of integrity models versus confidentiality models like Bell-LaPadula, and the Clark-Wilson model is often the correct choice when the question emphasizes separation of duties and transaction controls. A common trap is confusing it with the Biba model, which also addresses integrity but focuses on preventing data flow from lower to higher integrity levels rather than enforcing user-based constraints. Remember the memory tip: Clark-Wilson is all about "who can do what" through constrained interfaces and dual approval, making it the go-to for healthcare and financial systems requiring strict access separation.
This CISSP practice question tests your understanding of security architecture and engineering. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A health records system requires that doctors can write new records but cannot modify existing ones, and integrity is maintained through separation of duties. Which security model best fits this requirement?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Brewer-Nash
Why wrong: Brewer-Nash prevents conflict of interest, not integrity constraints.
Biba
Why wrong: Biba focuses on integrity but not separation of duties or constrained items.
Clark-Wilson
Clark-Wilson enforces transformation procedures and separation of duties to maintain integrity.
Bell-LaPadula
Why wrong: Bell-LaPadula is a confidentiality model, not integrity.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Clark-Wilson
The Clark-Wilson model enforces integrity through well-formed transactions and separation of duties, which directly matches the requirement that doctors can write new records but cannot modify existing ones. It uses constrained data items (CDIs), transformation procedures (TPs), and integrity verification procedures (IVPs) to ensure that only authorized users can perform specific operations, preventing unauthorized modifications.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Brewer-Nash
Why it's wrong here
Brewer-Nash prevents conflict of interest, not integrity constraints.
Biba
Why it's wrong here
Biba focuses on integrity but not separation of duties or constrained items.
Clark-Wilson
Why this is correct
Clark-Wilson enforces transformation procedures and separation of duties to maintain integrity.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Bell-LaPadula
Why it's wrong here
Bell-LaPadula is a confidentiality model, not integrity.
Common exam traps
The trap here is that candidates often confuse the Biba model with integrity enforcement, but Biba only prevents unauthorized data flow based on integrity levels, not the specific separation of duties and well-formed transaction constraints that Clark-Wilson provides for this scenario.
Detailed technical explanation
Under the hood, Clark-Wilson uses a triple of (user, TP, CDI) to enforce access rules; for example, a doctor might be authorized to execute a 'create record' TP on a CDI but not an 'update record' TP. In a real-world health records system, this prevents accidental or malicious alteration of patient data while allowing new entries, and integrity verification procedures (IVPs) periodically check that CDIs are in a valid state. The model also requires that all changes be logged, providing an audit trail that supports non-repudiation.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Security Architecture and Engineering — This question tests Security Architecture and Engineering — Read the scenario before looking for a memorised answer..
The correct answer is: Clark-Wilson — The Clark-Wilson model enforces integrity through well-formed transactions and separation of duties, which directly matches the requirement that doctors can write new records but cannot modify existing ones. It uses constrained data items (CDIs), transformation procedures (TPs), and integrity verification procedures (IVPs) to ensure that only authorized users can perform specific operations, preventing unauthorized modifications.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.
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