Every year in France, about 20000 citizens have to report for jury duty. The announcement of their designation represents the beginning of an experience marked by the discovery of a new world in which they have to construct a role they are hardly prepared. How they imagine in anticipation this original role ? And how those which have really accomplished it, experienced their participation in the assizes court and its effects ? This communication pretends to respond to these questions focusing the french juror's experience, their social and subjective issues. It is based on the results of a research conducted in the North of France, mixing observation, interviews and questionnaires.