‘Consent’ is one of the most important yet most contested notions in all of law and society. So much is done and so much is justified in its name: bargains, elections, sporting contests, medical procedures, personal relations and the like. Even if people act against what is thought to be their own best and future interests, their consent or agreement is often treated as being sufficient to confer legitimate approval on the decision or course of action chosen. A bad decision and its consequences are not set aside or mitigated by that fact alone if a person is adjudged to have consented to it. Not surprisingly, with so much riding on it, there is heated debate over what can count as adequate and endorsing consent in specific situations. For instance, while it is thought that consent must be freely given and not induced by threat or deception, there is widespread disagreement over the precise terms for evaluating the presence and quality of such contextual and vitiating conditions. Furthermore, the conditions for identifying sufficient consent will vary in relation to exactly what action is being excused or allowed.

Of course, one of the most crucial areas in which consent plays a central role is the criminal law. If people are thought to have consented to certain interactions with others or interferences by them, then such activity is treated as beyond the reach or purview of criminal charges and sanctions. This is nowhere more significant than in the realm of sexual activity. However, apart from the difficult issues surrounding the question of what is to count as valid consent (e.g., must an alleged rapist simply have an honest belief as to consent being given or must it also be a reasonable belief as well?), the law has chosen to place important limits on what exactly can be consented to – if ‘no’ means ‘no’, what does ‘yes’ mean?

In a relatively recent decision, English law had to grapple with the onerous and divisive issue of whether adults could consent to serious harm and injury in the course of controversial sexual encounters. The resulting court decisions managed not only to highlight the analytical complexity of such questions, but also to capture the fraught political, social, moral and psychological terrain that courts have to map and traverse in deciding such matters.