The expert report is the most substantial of the technical investigative measures. The judge appoints a technical expert to enlighten him on a question of fact: the profitability of a restaurant, the value of a business, the cause of a fall in turnover. The expert does not state the law and does not decide the dispute.
The procedure is adversarial. The parties send the expert written observations — the “dires”, a practitioners' term that does not appear in the code — which the expert must take into consideration and on which he must state, in his report, what action was taken.
The report is only one item in the debate: Article 246 specifies that the judge is not bound. Conversely, a private expert report, commissioned by one party alone, is never sufficient: the Court of Cassation held in a mixed chamber on 28 September 2012 that the judge may not rely exclusively on a non-judicial expert report produced at the request of one of the parties.
The Antibes case file contains both: the court-ordered expert report ordered by the Paris Court of Appeal, and private expert reports produced by each side.