Internal Res Judicata and Expert Witness Reports: The Court of Cassation Clarifies the Procedural Nature of Decisions on Court-Appointed Expert Examinations (Order No. 16034/2025)

In the complex landscape of Italian civil procedural law, the distinction between orders of a procedural nature and those with a decisive character is of crucial importance, especially when determining what can or cannot acquire the authority of res judicata. The Court of Cassation, with its Order No. 16034 of June 16, 2025, addresses a pivotal point, offering fundamental clarification regarding the nature of rulings concerning court-appointed expert examinations (CTU). This decision not only sheds light on an often-debated aspect but also provides valuable guidance for legal practitioners, ensuring greater certainty and flexibility in managing technical evidence.

The Case at Hand and the Issue of Internal Res Judicata

The Order in question, presided over by Judge E. Scoditti and reported by Judge G. Mercolino, originated from a dispute between Mr. P. (C. G.) and Mr. C. (R. F.). The issue arose following a ruling by the Court of Appeal of Genoa on 04/05/2018, which declared a decision inadmissible, laying the groundwork for the appeal to the Court of Cassation. At the heart of the debate is the delicate question of the legal nature of decisions relating to court-appointed expert examinations (CTU) and their capacity to acquire the authority of "internal res judicata." Internal res judicata is formed when a part of a judgment, not appealed or confirmed, becomes final within the same proceeding, precluding any further discussion on that specific point.

The Court of Cassation's Ruling: A Fundamental Clarification

The Supreme Court, with its Order No. 16034/2025, has issued a ruling of particular relevance, which deserves careful examination:

A decision that has exclusively ruled on the acceptability or unacceptability of the estimation method followed by the already conducted court-appointed expert examination, and possibly on the necessity of ordering a new expert investigation, even if contained in a non-final judgment, has a procedural nature and function and, therefore, does not prejudice the merits of the decision, remaining revocable and modifiable in the subsequent course of the proceedings; consequently, it is not capable of acquiring the authority of internal res judicata, which can only be formed on a minimal ruling of the judgment, consisting of the sequence represented by fact, law, and effect, capable of acquiring independent decisive efficacy within the dispute.

This ruling unequivocally clarifies that the judge's decisions concerning court-appointed expert examinations – such as assessing the estimation method adopted by the expert or the need for a new expert report – do not have a decisive character on the merits of the case. They are, rather, orders of a "procedural" nature and function. What does this mean in practical terms? It means that such rulings are aimed at managing the proceedings, collecting evidence, and instructing the case, not at definitively resolving a part of the dispute. Consequently, they are not capable of forming internal res judicata and can be revoked or modified by the judge during the proceedings, even if contained in a non-final judgment.

The principle is crucial: internal res judicata can only be formed on a "minimal ruling" of the judgment, i.e., on a decision that independently and definitively resolves a question of fact and law, linking a fact to a rule and producing a legal effect. Evaluations instrumental to evidence, such as those concerning the CTU, which are governed by Articles 196 and 279 of the Code of Civil Procedure and maintain their flexibility throughout the duration of the proceedings, do not fall into this category.

Practical Implications for Civil Proceedings

The consequences of this ruling are significant for legal practice and the management of civil proceedings:

• **Greater Evidentiary Flexibility:** The judge retains full freedom to evaluate and, if necessary, modify their decisions on court-appointed expert examinations, without being bound by premature res judicata on merely procedural or technical aspects.
• **Protection of the Right to Evidence:** Parties can continue to request new evaluations or additions to the court-appointed expert examination, even if a previous order had expressed an opinion on the method or the need for further investigation, without the risk of definitive preclusion.
• **Focus on the Merits:** The ruling reaffirms that proceedings must aim at deciding the merits of the dispute, preventing instrumental issues from rigidifying the decision-making process.
• **Legal Certainty:** While ensuring flexibility, the Court of Cassation provides a clear criterion for distinguishing between what is susceptible to res judicata and what is not, contributing to the predictability of judicial decisions.

Conclusions

Order No. 16034 of 2025 by the Court of Cassation represents an important milestone in the debate on the nature of decisions concerning court-appointed expert examinations and the formation of internal res judicata. By reiterating the procedural nature of rulings on CTU, the Supreme Court ensures that civil proceedings maintain the necessary flexibility for ascertaining material truth, without instrumental decisions prematurely precluding the possibility of a complete and thorough investigation. This ruling is an example of how jurisprudence evolves to adapt to the practical needs of proceedings, while simultaneously safeguarding the principles of legality and due process.