This article makes the case for greater attention to be given to the role of national legal culture in the making and practice of international law. The merits of this contested notion as a tool for gaining new insights are discussed, as is the legal cultural approach embedded in the broader field of study known as "comparative international law". In an effort to demonstrate the utility of engaging with this concept, the focus turns to the inner legal culture of international law, which is composed of lawyers, judges and other professionals. It is argued that there are two factors of influence which allow for domestic elements to seep into international law. The first relates to individuals, via the inculcation of parochial values, whereas the second takes on a structural dimension, through inter alia the general principles of law and the "equitable geographical representation" requirement found in the statutes of many intergovernmental bodies. This theoretical framework is subsequently applied to the International Court of Justice, a suitable case study on account of it being a meeting place of various juridical traditions. At the individual level, judges and counsel appearing before the ICJ are considered. As regards the structural level, certain institutional features conducive to domestic influences are highlighted. Finally, the article identifies and briefly discusses three themes in the jurisprudence of the ICJ where national legal cultures have left their mark: analogies to municipal law, the manner and style in which the outcome of cases are justified and the debates surrounding the standard of proof.