Voluntariness is a necessary condition of valid consent. But determining whether a person consented voluntarily can be difficult, especially when people are subjected to coercion or manipulation, placed in a situation with no acceptable alternative other than to consent to something, or find themselves in an abusive relationship.

Maximilian Kiener is a Junior Professor of Philosophy and Ethics at Hamburg University of Technology, Germany, and an Associate Member of the Faculty of Philosophy at the University of Oxford, UK. He specialises in moral and legal philosophy, with a particular focus on consent, responsibility, and artificial intelligence. He is editor of The Routledge Handbook of Philosophy of Responsibility (2023).