We are entering a new chapter in the digitalisation of society, advancing from machines as decision support, to machines as “decision makers” (in one sense of the word). This is made possible by the many breakthroughs in the development of artificial intelligence (AI) in the last decade. There is reason to expect that AI will be used increasingly not only for private decisions, but also for decisions made by public authorities and institutions. The implementation of AI in public decision making has raised concerns in many quarters and led to much discussion among philosophers, legal scholars, and social scientists. Who is responsible when a machine commits a serious error?