The concept of vulnerability is increasingly being incorporated in the case-law of the European Court of Human Rights. This article is not aimed at providing a descriptive overview of the cases in which such a concept has been addressed by the Court, with a view to reconstructing its definition, nor is it aimed at reconceptualising, from a normative standpoint, the content of the notion of vulnerability as it emerges from the Court's case-law. Rather, the article first seeks to investigate whether it is possible to define the notion of vulnerability in an abstract sense and then to delineate a definitional model which, departing from mandatory definitions and open definitions, is instead grounded on presumptions.