When an expert opinion has been requested, two experts are appointed, one by the examining magistrate and the other by the person concerned. The investigating magistrate will set a time limit for the latter to do so, but he or she has the right to explicitly waive the appointment and defer to the conclusions of the expert appointed by the judge. If the interested party, without having waived his right, has not appointed his expert within the time limit set, the expert is appointed ex officio by the examining magistrate. Experts are chosen from special lists of experts drawn up in each jurisdiction by the appeal courts or judicial tribunals.
The interested party has the right to choose his expert from outside the official lists, but if he does so, his choice is subject to the approval of the examining magistrate. The investigating judge’s order defines the mission given to the experts.