After three years in High school, most Students do not really know what their career will be. Of course Teachers try to help, but having a vocation at that age is very rare. In most cases, students just choose the subjects in which they are told they will be good at, and then try to integrate a Classe préparatoire aux Grandes Ecoles because it is supposed to be the best way to have a good job.
Once you have been admitted in one of these prestigious schools, it can be difficult to move to a different field. Particularly regarding Law studies, since there is no official equivalence between such “Grandes écoles” and Law. Moreover going to University can be seen as a failure.
However the Grande Ecole de Droit offers quite a unique opportunity. Indeed it allows students to join after two years of CPGE directly as a second year student after passing an exam based on the first year courses in Law.