International legal scholarship in Brazil follows nowadays a new legal realism approach. The idea is to apply empirical techniques to construct and present International Law, in order to identify the material conditions within which those rules are created and applied. Although this trend is relevant to improve international legal studies, this paper presents a phenomenological warning based on Husserl’s theoretical approach. According to this perspective, in spite of the collected empirical experience, it is the categorical position of the researcher which defines its meaning. We argue that, although sense is somehow related to an empirical significant, empirics itself possesses an empty meaning, as the signification process is not really bound to it. In this sense, the origins and the effectiveness of International Law cannot be explained solely by empirics itself: not only it is important to embody and apply empirical techniques in international legal scholarship, but also to remember that the limits of international legal rules also derive from imaterial conditions related to the categorical position of those who learn and apply them.