Child welfare, in France or elsewhere, brings question the juvenile justice and its consequences (its adaptation in educational terms). Educational organizations, and within, them governing, their age of legal responsibility, childhood must be discussed. The legal definition of childhood as conceived by the modernity since the Convention of New York , scrambles the reference marks with for consequence some counter- productive effects for the child himself. A polemic settled between "traditionalists " and "liberationists ". For lack to agree a politico-ethics definition of childhood, one observes a blur and the child-subject of law remains to be invented . This work who is beginning trough the DEA, is not a study of social-education, no an unspecified sociological, therapeutic analysis of social problems, delinquency or ill-treatment of children. It builds upon the childhood history (Ariès and Boswell ), the one of the thought of the childhood trough Humes, Lockes, Rousseau and continued with Hannah Arendt, Onora O'Neill...It considers the searches of John Rawls , Ronald Dworkin . It does not examine justice as such, but at the particular moment where it orders an educational sentence. Thus it should be given for objective to check whether the concept of childhood as it comes from modernity, and since the Convention of New York and what scrambles the traditional reference points, complicates the legal solutions for the child in danger, to analyse some counter-productive effects. The assumption of the childhood lies in a paradigmatic ambiguity of the definition of the child which, by indication as a subject of law or object of law, would produce a contradiction whose paradoxical character poses questions. If the concept of subject of law, derived from the French Revolution, tits in with the concept of freedom, the result, for childhood, perverts the philosophical intention. The concepts of law credit, from reward justice, linked to the subject of law, would lead to subversion of the right to childhood. Conversely the concept of object of law, resulting from a singular definition of the minority (according to the limit with the paternal law), consistent with a resolving design justice based on law-freedom, would seem more respectful of otherness and the subjectivity of the infant. The repressive evolution of the legal sentences for the minor can be astonishing. Our work, linked with the consequences of the Declaration of the Rights of the Child, analyses its effects. It explains the human net- connections into which the child is catching between different partners, the complex character of the systems and their educational answers, the "judiciarysation", the lack of imagination of the projects. It attempts to understand a confused unit from which the child, subjected to a great number of changes , becomes an object of law. Practice gives lie to the law hoped for New-York. How, in legal action, the sentence of education, can the concept of subject of law be integrated while respecting that childhood ?. .