Respondeat inferior? Subsidiaries' liability for parents' antitrust infringements: A competition and private law perspective on the Sumal judgment of the European Court of Justice

In Sumal the ECJ confirmed that ‘innocent’ subsidiaries can under certain conditions be held liable to pay compensation in competition damages actions alongside their parent company. To do this, it transplanted the concept of undertaking to the private enforcement of competition law. This article discusses the effect of this apparent derogation from the principle of legal personality under the lens of both competition and private law. It is argued that the ruling confirms the continuing drive by the ECJ to create a more effective regime of damages actions but could lead to significant difficulties for the public enforcement system as well as for private law doctrine.