The Oversight Board, an independent body established by Meta Platforms Inc. to make decisions and recommendations regarding difficult and consequential content moderation questions on Facebook and Instagram, represents a unique experiment in self-regulation of ethical dilemmas in the tech industry. This colloquium will explore the work and experience of the Oversight Board in its first three years of operating, and the challenges that it faces in bringing a sound and effective normative framework to bear on the distinctive difficulties of content moderation at scale. The Institute for Ethics in AI will bring together world-leading philosophers and other experts in the humanities with the technical developers and users of AI in academia, business and government. The ethics and governance of AI is an exceptionally vibrant area of research at Oxford and the Institute is an opportunity to take a bold leap forward from this platform. Every day brings more examples of the ethical challenges posed by AI; from face recognition to voter profiling, brain machine interfaces to weaponised drones, and the ongoing discourse about how AI will impact employment on a global scale. This is urgent and important work that we intend to promote internationally as well as embedding in our own research and teaching here at Oxford.