The so-called “right to be forgotten” has been put firmly on the agenda, both of academia and of policy. Although the idea is intuitive and appealing, the legal form and practical implications of a right to be forgotten have hardly been analysed so far. This contribution aims to critically assess what a right to be forgotten could or should entail in practice. It outlines the current socio-technical context as one of Big Data, in which massive data collections are created and mined for many purposes. Big Data involves not only individuals’ digital footprints (data they themselves leave behind) but, perhaps more importantly, also individuals’ data shadows (information about them generated by others). And contrary to physical footprints and shadows, their digital counterparts are not ephemeral but persistent. This presents particular challenges for the right to be forgotten, which are discussed in the form of three key questions. Against whom can the right be invoked? When and why can the right be invoked? And how can the right be effected? Advocates of a right to be forgotten must clarify which conceptualisation of such a right they favour – a comprehensive, usercontrol-based right to have data deleted in due time, or a narrower, context-specific right to a “clean slate” – and how they think the considerable obstacles presented in this paper can be overcome, if people are really to be enabled to have their digital footprints forgotten and to shun their data shadows.
