Abstract Data are undoubtedly a contested commodity. On the one hand, data commodification is largely under way including through the operation of law. This is notably visible with the new EU data policy (Data Strategy notably followed by the Data Act, the Data Governance Act) that aims to establish data markets in keeping with European values. On the other hand, this phenomenon is heavily contested based on a wide range of different arguments, which have not been subjected to a systematic clustering. Data commodification is often understood simplistically as a binary and monolithic phenomenon whereby data would be either ‘commodified’ or not. This leads to misunderstandings of this phenomenon and of the ways in which it manifests. For example, many conceptual misunderstandings surround the relationship between ‘data access’ or ‘data sharing’ and data commodification and markets. This paper clarifies the phenomenon of data commodification, by approaching it as a spectrum with degrees following M. J. Radin (Contested Commodities, 1996). Following Radin, the paper clusters the different data governance arguments – or even paradigms – found in the literature along a data commodification spectrum. A specific attention is paid to the importance of market discourses in commodification dynamics, especially on the law. The paper offers a novel systematic synthesis of the data governance normative arguments, including data commons, data trusts, data sharing, data intermediation, against the background of the data commodification phenomenon. This synthesis brings conceptual clarity and allows to bring together different strands of the data literature (especially welfare economics, law and economics, commons, critical data studies, infrastructure studies) comprehensively, while they have until now remained siloed. Data governance normative arguments would greatly benefit from taking into account (conceptual and/or normative) arguments found in other strands of the literature. The paper can also be used to evaluate how data governance arguments or legislations relate to data commodification and take into account the specificities of data, thus enabling for more systematic analysis. The paper finds that data is actually a very contested commodity: The very conceptualization of data as a commodity is ontologically contestable. The framework in which situations are conceptualized – whether as data market ones or not – can indeed play a powerful but often invisible discursive role on commodification dynamics. Finally, the very identification and regulation of ‘data’ alone necessarily brings about certain commodification affordances.