Responsibility for Data Protection in a Networked World: On the Question of the Controller, “Effective and Complete Protection” and its Application to Data Access Rights in Europe Mahieu René van Hoboken Joris Asghari Hadi In the current networked world, almost no system in which personal data is processed stands on its own. For example, websites and mobile applications integrate third party services for behavioral targeting, user analytics, navigation, and many other functionalities. Governments build central infrastructures to share data efficiently between different branches of government and with other organisations. This paper analyses the current system in Europe for determining who is (or better, are) responsible for observing data protection obligations in such networked service settings. In doing so we address the following problems: (1) of ambiguity in applying the concept of data controller in networked settings; and (2) of insufficiencies in the framework for establishing the extent of the responsibilities in situations of joint control. We look at how the law and regulators address these problems and how the European Court of Justice tackles these problems by applying the principle of “effective and complete protection”. The issue of joint responsibility has gained particular relevance in the wake of Wirtschaftsakademie, a case recently decided by the European Court of Justice. In this case, a Facebook fan page administrator was found to be a joint-controller and therefore jointly responsible, together with Facebook, for observing data protection rules. Following this decision, there are many more situations of joint control than previously thought. As a consequence, part of the responsibility for compliance with data protection legislation and risk of enforcement measures are moved to those who integrate external services. This will change the incentive structure in such a way that joint-controllers will place a much higher value on data protection. To explore the practical implications of the legal framework, we analyse a number of examples taken from our earlier empirical work on the right of access to reflect on the newly emerging data responsibility infrastructure. We show that the coordination of responsibilities is complex in practice because many organisations do not have a clear overview of data flows, there are power imbalances between different actors, and personal data governance is often happening in separated specialised units. C-210/16 Wirtschaftsakademie GDPR access rights data controller joint-control principle of “effective and complete protection” right of access 340 periodical academic journal JIPITEC 10 1 2019 84 104 2190-3387 urn:nbn:de:0009-29-48796 mahieu2019