Official expert opinions in road and building disputes operate at the interface of engineering knowledge and judicial decision-making. Their vulnerability often arises not from a lack of technical expertise, but from breaks in the chain connecting the court order, professional competence, evidence, analytical method, causation, quantification, and the final answer. This professional-conceptual article develops an integrated quality-control framework for producing expert opinions that are traceable, reproducible, proportionate to the available evidence, and more defensible under adversarial review. The framework is derived from an analytical synthesis of current Iranian rules governing official expert practice and civil procedure, together with forensic-engineering guidance and recent literature on expert-evidence reliability, construction claims, delay analysis, and construction-forensic ethics. The proposed model treats the expert opinion as an eight-link evidentiary chain: jurisdiction and mission control; order audit; evidence architecture; chronology; technical and causal analysis; transparent quantification; item-by-item response to the referral questions; and adversarial quality review. Four epistemic levels are proposed to separate documented facts, strong corroborative indications, technical probabilities, and party allegations. In addition, a Claim-Evidence-Finding matrix and a final PASS audit—Professional jurisdiction, Accuracy, Scope, and Sustainability—are introduced as practical tools. The central proposition is that defensibility is produced by traceability and methodological discipline rather than rhetorical certainty. The framework is applicable, with case-specific adaptation, to defects and failures, construction accidents and HSE, contractor claims and delays, damages, and building appraisal. As a conceptual professional framework, it requires future empirical evaluation across real expert reports and higher-panel reviews.