Robert Alexy is Professor of Public Law and Legal Philosophy at Kiel University, Germany.Ralf Poscher is Director of the Department of Public Law at the Max Planck Institute for the Study of Crime, Security and Law, Germany.Rafael Giorgio Dalla-Barba is Doctoral Researcher at the Max Planck Institute for the Study of Crime, Security and Law, Germany.David Duarte is Associate Professor of Law at the University of Lisbon, Portugal.

• Introduction: A Brief Overview of the Alexy-Poscher Debate, Rafael Giorgio Dalla-Barba (Max Planck Institute for the Study of Crime, Security and Law, Germany)First Round1. On the Structure of Legal Principles, Robert Alexy (Kiel University, Germany)2. Insights, Errors, and Self-Misconceptions of the Theory of Principles, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Second Round3. Ideal ‘Ought’, Robert Alexy (Kiel University, Germany)4. Theory of a Phantom: The Principles Theory’s Futile Quest for its Object, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Third Round5. Ideal ‘Ought’ and Optimisation, Robert Alexy (Kiel University, Germany)6. Resuscitation of a Phantom? On Robert Alexy’s Latest Attempt to Save His Concept of Principle, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Conclusion: The Alexy-Poscher Debate: Working on the Problems and on the Solutions, David Duarte (University of Lisbon, Portugal)

Robert Alexy is Professor of Public Law and Legal Philosophy at Kiel University, Germany.Ralf Poscher is Director of the Department of Public Law at the Max Planck Institute for the Study of Crime, Security and Law, Germany.Rafael Giorgio Dalla-Barba is Doctoral Researcher at the Max Planck Institute for the Study of Crime, Security and Law, Germany.David Duarte is Associate Professor of Law at the University of Lisbon, Portugal.

• Introduction: A Brief Overview of the Alexy-Poscher Debate, Rafael Giorgio Dalla-Barba (Max Planck Institute for the Study of Crime, Security and Law, Germany)First Round1. On the Structure of Legal Principles, Robert Alexy (Kiel University, Germany)2. Insights, Errors, and Self-Misconceptions of the Theory of Principles, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Second Round3. Ideal ‘Ought’, Robert Alexy (Kiel University, Germany)4. Theory of a Phantom: The Principles Theory’s Futile Quest for its Object, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Third Round5. Ideal ‘Ought’ and Optimisation, Robert Alexy (Kiel University, Germany)6. Resuscitation of a Phantom? On Robert Alexy’s Latest Attempt to Save His Concept of Principle, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Conclusion: The Alexy-Poscher Debate: Working on the Problems and on the Solutions, David Duarte (University of Lisbon, Portugal)

Robert Alexy is Professor of Public Law and Legal Philosophy at Kiel University, Germany.Ralf Poscher is Director of the Department of Public Law at the Max Planck Institute for the Study of Crime, Security and Law, Germany.Rafael Giorgio Dalla-Barba is Doctoral Researcher at the Max Planck Institute for the Study of Crime, Security and Law, Germany.David Duarte is Associate Professor of Law at the University of Lisbon, Portugal.

• Introduction: A Brief Overview of the Alexy-Poscher Debate, Rafael Giorgio Dalla-Barba (Max Planck Institute for the Study of Crime, Security and Law, Germany)First Round1. On the Structure of Legal Principles, Robert Alexy (Kiel University, Germany)2. Insights, Errors, and Self-Misconceptions of the Theory of Principles, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Second Round3. Ideal ‘Ought’, Robert Alexy (Kiel University, Germany)4. Theory of a Phantom: The Principles Theory’s Futile Quest for its Object, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Third Round5. Ideal ‘Ought’ and Optimisation, Robert Alexy (Kiel University, Germany)6. Resuscitation of a Phantom? On Robert Alexy’s Latest Attempt to Save His Concept of Principle, Ralf Poscher (Max Planck Institute for the Study of Crime, Security and Law, Germany)Conclusion: The Alexy-Poscher Debate: Working on the Problems and on the Solutions, David Duarte (University of Lisbon, Portugal)