Contestations about the contents and validity of laws and legal principles are fundamental to the (international) legal profession. After all, when engaging with legal norms, disagreements about their meaning and validity a central part of the day-to-day work of legal professionals specialising in international law, including legal counsel representing governments, international judges, legal officers working for international organisations and non-governmental organisations, and legal academics. We propose a practice-oriented approach to empirically research such interpretive legal contestations by groups of legal professionals. Using an interdisciplinary perspective, we contribute to IR norms research by drawing on not only IR practice theory, but also Bourdieu-inspired research within the Sociology of International Law and ongoing discussions on legal realism in International Legal Theory, including what we have called European New Legal Realism. After outlining how to implement our approach using either a Bourdieusian perspective or the concept of communities of practice, we use normative contestations in and around climate change law to illustrate its added value. Such an approach not only promises to make interpretive legal contestations visible empirically, but also emphasises how interpretive legal contestations matter as they reflect underlying power dynamics and may result in normative legal change in practice.