Professor David Isaacs is a consultant paediatrician at the Children's Hospital at Westmead, Sydney, and Clinical Professor in Paediatric Infectious Diseases at the University of Sydney. He has been a member of every Australian national immunisation advisory committee for the last 25 years. He is passionate about bioethics, and has published and taught extensively on ethical aspects of immunisation. He is also one of several doctors who have exposed what they say is a culture of violence, abuse, self-harm and cover-up on Nauru, in defiance of laws that could land them in prison.