The legal expert is a professional practitioner: architect, doctor, engineer, social investigator…
The judge asks experts to give their qualified opinion on facts in the aim of shedding light on the case. To do this, the expert takes the oath in front of the court.
Experts are on a list made up for each appeal court. They are paid in fees, the amount being fixed by the judge, except in criminal cases when the fee is fixed by the texts.