abstract Many people assume that invasive research on animals is justified because of its supposed benefits and because of the supposed mental inferiority of animals. However probably most people would be unwilling to sign a living will which consigns themselves to live biomed-ical experimentation if they ever, through misfortune, end up with a mental capacity equivalent to a laboratory animal. The benefits would be greater by far for medical science if living will signatories were to be used, and also the mental superiority boast would no longer apply. Ultimately, it is argued that invasive biomedical experiments would be unacceptable in a democratic society whose members are philosophically self-consistent.