Instead than denouncing the misunderstandings of legal formalism, mostly an invented formalism, we have to deepen our work on the forms of the law within which, paradoxically, one must count for the very forms of vagueness in the law, their varieties, their fidelity to the law and reasoning with vague concept in law. The law treats vagueness in an original way which constitutes a challenge to its analysis and technical approaches in the philosophy of language.