If there is one area in which passion is expressed in all its forms, it is that of refereeing. During a competition, whether local or international, everyone has a reading of what happens on the tatami according to objective but also subjective criteria. What makes complex judo refereeing is that one does not measure a distance or a time, but one appreciates a technique and the referee at the center of the arena must react immediately. If the principle of the sport is easy to understand, since it is necessary to throw the opponent on the back with force, speed and control (ippon), the estimation of the techniques and the values ​​which are attributed to them is a science which calls upon many skills.