Legal systems operate on a pain principle: punishments should involve a loss, and that loss should be painful. The problem is, some of us feel some losses more keenly than others: one person might find prison life merely unpleasant and difficult, while another could spend their entire prison term in a constant state of fear and distress. Have these two prisoners been punished equally? What legal and ethical consequences arise from cases like this? Join philosopher Lauren Ware (University of Stirling) to consider the radical proposal that prisons should be turned into personalised pain factories.