He was the Nathaniel Fensterstock Visiting Professor of Law at Columbia Law School, New York, USA in 2025 and the Robert S. Campbell visiting professor at Magdalen College, University of Oxford, UK in 2011-2012. He has also held visiting positions at the Max Planck Institute for the Study of Crime, Security and Law, Freiburg, Germany (2024), Sciences Po, Paris, France (2019), Ludwig Maximilians University in Munich, Germany (2011), the French National Centre for Criminology (CESDIP) in Paris, France (2011), and at the Australian National University, Canberra, Australia (2008). Until 2013, he held the Canada Research Chair in Crime, Security, and Constitutionalism at Queen’s University, Kingston, Canada. He served as law clerk to Justice Louis Lebel at the Supreme Court of Canada on 2000-2001.
He was educated at the University of Toronto (BA, philosophy, JD law), the University of Pennsylvania (MA philosophy) and Columbia University (LLM, SJD law).
His writing focuses on theoretical issues in criminal justice and public law including criminal law and procedure, sentencing, policing, and constitutional questions of rights and proportionality reasoning. He is the editor of two books: The Philosophical Foundations of Constitutional Law (with David Dyzenhaus) and The Dignity of Law (with Dwight Newman). His work has appeared in such publications as the Yale Law Journal, Ratio Juris, the Boston University Law Review, the University of Toronto Law Journal, Criminal Law and Philosophy and many books. He is a member of the editorial boards of the journals Law and Philosophy and Criminal Law and Philosophy.
