This thesis investigates the normative transformation enacted by the legal praxis of international courts and proposes a mid-range theory to understand how courts formulate their jurisprudential policies. The thesis advances that courts are ‘transformative venues’ and legal praxis comprises ‘transformative practices’. This claim is built upon a systematic analysis of how the norm against torture and inhuman or degrading treatment under the European Convention on Human Rights has developed over time. More specifically, this analysis traces how the rulings of the European Court of Human Rights have been the vehicles of this normative transformation. The findings of this analysis are supplemented with the insights gathered through a fieldwork at the Court and semi-structured expert interviews. The theory that is developed based on this analysis proposes that courts have identities, and that these identities shape courts’ preferences and, ultimately, their practices. This theory also shows that the trajectory of norm development is not linear and progressive. Rather, norms are constantly performed through legal practice, which generates not only non-linear norm development but also instances of norm regression or the obstruction of norm development. In essence, this research bridges International Relations and International Law, and sheds light on the practices of international courts and the development (and occasional reversals) of norms that these practices generate.