Although formal documents such as confessions, testimonies, and oaths are recognized under Iran’s civil law, they have notable limitations, particularly in complex, technical, or specialized cases where comprehensive accountability is required. In lawsuits seeking compensation for losses and in civil liability cases, judges often issue a writ of advisory opinion, referring the matter to experts in relevant fields to investigate, calculate, and estimate each party’s degree of fault (liable and loss-incurred). These experts assess the case and determine the percentage of responsibility assigned to each party. Regarding the nature of advisory opinions, there is some disagreement. One group of jurists views them as a form of testimony, asserting that conditions such as numerosity and justice must be met for the opinion to be valid. Another group emphasizes their independent character, holding that certainty alone is sufficient to validate the opinion. In judicial practice, advisory opinions are considered valid to the extent that they specify the compensation amount payable by the liable party. Consequently, expert opinions can serve as an independent justificatory proof among other evidences and, in some cases, may even be regarded as superior. This study employs an analytical-descriptive approach to examine and evaluate the nature and validity of advisory opinions in comparison with other forms of justificatory evidence.
