This measure involves technical or scientific investigations in the field of medecine or criminology carried out with the aim of searching for clues or information that may be useful in revealing the truth. In the context of an investigation, the Code of Criminal Procedure provides for the possibility of having recourse to experts' conclusions/findings or technical or scientific examinations as well as to all persons who, it is considered, may be in possession of items relevant to the investigation. The authority competent to undertake this measure is the officer of the judicial police, or under it's supervision, the agent of the judicial police, in cases of offences or serious crimes in flagrante delicto (articles 60, 60-1 and 60-2 of the Code of Criminal Procedure), or the officer of the judicial police acting on the authorisation of the public prosecutor, or the public prosecutor himself/herself in the context of a preliminary investigation (articles 77-1, 77-1-1 and 77-1-2 of the Code of Criminal Procedure). In the context of a judicial investigation the investigating judge can, if there is a technical question, order an expert evaluation, either on his own motion, at the request of the parties or at the request of the public prosecutor (article 156 of the Code of Criminal Procedure). He makes an order appointing an expert, determining the task required of the expert and the deadline by which the expert must submit his/her expert's report. The trial court can also order the provision of additional information and can appoint an expert under the same conditions (articles 434 and 463 of the Code of Criminal Procedure).
Criminal liability of an expert :
The expert may incur criminal liability. For instance he will be criminally liable for the following offenses : violation of professional confidentiality (art. 226-13 of the criminal code), corruption (art. 434-9 of the criminal code) or falsification of the results of the expertise (art. 434-20 of the criminal code).