Court of Cassation, 3rd Civil Chamber, 8 January 2026, No. 23-22.803
The general principle: an out-of-court expert report is not sufficient on its own
An out-of-court expert report commissioned at the request of a single party, even if that party is a party to the proceedings, cannot in itself serve as the basis for a judicial decision. The judge is required to examine it, but must corroborate it with other evidence. This is the rule established by the Court of Cassation since 2012, justified by the greater safeguards offered by judicial expert reports — ordered by the judge, governed by law and subject to cross-examination — compared to expert reports carried out outside any judicial proceedings.
The facts: a dispute concerning project management
Judgment of the Court of Cassation
The Third Civil Chamber dismissed the appeal and held that: whilst a judge may not base his decision exclusively on a non-judicial expert report commissioned at the request of one party, the situation is different where the expert report has been carried out in accordance with a contract concluded between the parties and by an expert chosen by mutual agreement. In such a case, the judge may exercise his/her discretion to assess the value and scope of the expert report, without being required to corroborate it.
Why this distinction?
The decisive factor lies in the joint appointment of the expert, and thus in the principle of the parties’ contractual freedom and the binding nature of contracts. However, the probative value of the report remains, subject to the judge’s assessment, and the actual quality of the expert opinion remains decisive. In practice, this solution encourages parties to make expert determination arrangements contractually before any dispute arises.
