British academic lawyer Professor Sir Ian Kennedy explores the concepts of modern medicine in the fifth Reith lecture from his series entitled 'Unmasking Medicine'. In this lecture entitled 'The Doors of Mental Illness', Professor Kennedy explores the concepts of mental illness. Professor Kennedy questions the responsibility and power placed in the hands of medical experts and evaluates how mental differences are treated in society. He considers what mental health really is and demonstrates the shaky ground that the concept of mental illness rests on. Is it a medical complaint or is it a judgement created by society to highlight abnormalities?