Can an expert report commissioned by one party alone found the judge’s decision? Since 2012 the answer has been a single rule: no if it stands alone, yes if it is corroborated. What remained was to know what counts as corroboration. The reported decision of the Commercial Chamber of the Cour de cassation (the French supreme court for civil and commercial matters) of 1 April 2026 answers that the documents annexed to the report itself are enough, provided they are not the expert’s own work. For anyone commissioning a property valuation for litigation, the lesson is practical: the evidential weight of the report lies in what it annexes.
The facts
A French supplier delivered beef to an Italian food manufacturer for ready meals. In February 2013, during the horse-meat affair, tests revealed horse meat in one batch; the supplier quarantined all its Romanian-sourced supplies, and the Italian authorities seized and then destroyed all the batches made from its products. The manufacturer’s insurer, subrogated after paying out, sued the supplier and its insurer.
To quantify the loss, the insurer produced an expert report drawn up at its request by a private firm, filed on 11 October 2013, which put the overall loss at €7,008,271. On 30 May 2024 the Versailles Court of Appeal, ruling after an earlier cassation, ordered the supplier’s insurer to pay €2,200,000. That insurer appealed: the judge cannot rely exclusively on a non-judicial expert report whose opposability the other party disputes, and the documents attached to the report are inseparable from it; the Court of Appeal had therefore breached article 16 of the French Code of Civil Procedure.
The decision
The Cour de cassation dismissed the appeal (Cass. com., 1 April 2026, appeal no. 24-17.785, reported).
It laid down the rule: “the judge may base his assessment on a non-judicial expert report drawn up at the request of one of the parties, provided that the content of that document is corroborated by documents, even if annexed to the report, which are not the expert’s own work” (translated from the French).
It then applied it: the Court of Appeal had found that the report was “corroborated by the accounting documents, orders, invoices and credit notes” of the manufacturer “which are annexed to it and on which the expert based his conclusions”. Those documents, “taken from the accounts” of the company, “were not the expert’s own work”; the Court of Appeal could therefore rely on the report to fix the sums due.
What this changes for the valuation
The 2012 rule stands. A mixed chamber held on 28 September 2012 (appeal no. 11-18.710) that the judge cannot base his decision exclusively on an expert report commissioned by one of the parties. The Cour de cassation restated it in 2025 and 2026, with qualifications: an undisputed fact, an expert chosen by mutual agreement under the contract. The decision of 1 April 2026 does not set the rule aside; it clarifies corroboration, which may come from inside the report, as long as the annexed documents have an existence of their own.
What is not the expert’s own work. In a property valuation, these are the sale deeds and extracts from the public land-transaction database that support the comparables, the leases and rent receipts that support the rental value, the annual accounts and tax returns that support the value of a business or of shares, the planning documents, the surveys, the contractors’ quotes, the bailiff’s reports. What is the expert’s own work is the selection, the weighting, the calculation and the conclusion. A report that cites references “from our databases” without producing them does not corroborate itself; a report that annexes the deeds does. Nor is the annex the only route: a document cited by the report and disclosed by the lawyer in the list of exhibits plays the same part, since what matters is where the document comes from and whether it is before the court (articles 7, 15 and 132 of the French Code of Civil Procedure), not where it is stapled. What is not enough is a reference to a document nobody produces: the judge cannot open it, and it remains the expert’s word.
A report is built to be checked. The Charte de l’expertise en évaluation immobilière (the French property valuation charter) describes the expected content of a report, with the identification of sources and the documents examined (6th edition, November 2025, Title II, chapter 10), and the European Valuation Standards require that the report allow the reader to follow the reasoning through to the conclusion (EVS 5). The decision gives these requirements a direct judicial effect: the report a judge may rely on is the one in which every figure refers to a document the opponent can discuss.
The format remains a choice. A properly annexed single-party report is admissible and may be relied upon. A joint private valuation (expertise amiable conjointe), where the other party is invited and may submit observations, carries more weight, and a court-ordered appraisal (expertise judiciaire) binds both sides. Depending on the stakes, the stage of the proceedings and the opponent’s attitude, one format or another is appropriate; in every case, the annexes make the difference.
What the expert takes from it
- Corroboration of a private report may come from its own annexes, if they are not the expert’s own work.
- The documents to annex, or to have the lawyer disclose, are the raw ones: deeds, leases, accounts, planning documents, surveys, quotes. The expert’s calculations and tables corroborate nothing.
- A report delivered without its sources is argued over; a report delivered with its sources is verified.
- The 2012 rule remains: an uncorroborated single-party report is not enough, even if the other side was invited.
- The choice between a single-party report, a joint private valuation and a court-ordered appraisal is made at the start of the assignment, according to its intended use.
Further reading
The Court expert and litigation support page describes the assignments, their timescale and their fee. The guide Producing a valuation in a French court: which format? and the glossary entries expertise amiable conjointe and seconde lecture complement this article. On the same theme: Private expert reports: what a French judge can do with them, 2025 and 2026 and What a valuation report contains. The decision is available on Légifrance.
What next
Do you need to produce a valuation in a French court?
My report annexes the documents it rests on: sale deeds, leases, accounts, planning documents. That is what allows the judge to rely on it, even without a court-ordered appraisal.
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