This article revisits the traditional conception on the study of the sources of international law by contrasting it with one of the notions that challenges classical law making: soft law. In doing so, the article presents an overall review of the concept of soft law, exploring its main features and actual legal implications. Finally, the paper formulates a series of questions whose main aim is to make a call for rethinking the sources of international law. It is posited here that such sources should not remain static but rather develop at the speed of contemporary international relations. Special reference is made to international environmental law considered as a particular branch of international law, which dynamics are to be useful and pertinent to such an endeavor.