Recognizing that inclusion of 'groups' or 'concerns' in the assessment of antitrust enforcement is essential to prevent undertakings from circumventing the Treaty's antitrust provisions, the author of this in-depth analysis critically evaluates relevant ECJ cases and Commission pronouncements in order to determine whether current practice under the single economic entity doctrine amounts to an appropriate and effective enforcement of this increasingly significant aspect of European competition law. Among the issues and topics analysed are the following: the group or concern privilege under Article 101 (1) TFEU; the application of the single economic entity concept for the attribution of liability; the burden of proving 'decisive influence'; the parent company's rights of defence; corporate reorganizations; 'piercing the corporate veil'; control versus dominance; the requisite degree of control; potential versus actual control; the standards of legal separation and organizational autonomy; the existence of a common commercial strategy or financial dependence; and the extension of jurisdiction in antitrust matters. In a framework of analysis drawn up in the final chapter, policy considerations are presented that not only reflect accurately the underlying purpose of the single economic entity doctrine, but also show ways to incorporate the global component in effective enforcement of European competition law. Bringing at last a great measure of legal certainty to the 'parent-subsidiary-liability debate' in European competition law, this book will be welcomed by practitioners, policymakers, and academics concerned with theory and practice in the field.