Scientists have a choice concerning what role they should play in political debates and policy formation, particularly in terms of how they present their research. This book is about understanding this choice, what considerations are important to think about when deciding, and the consequences of such choices for the individual scientist and the broader scientific enterprise. Rather than prescribing what course of action each scientist ought to take, the book aims to identify a range of options for individual scientists to consider in making their own judgments about how they would like to position themselves in relation to policy and politics. Using examples from a range of scientific controversies and thought-provoking analogies from other walks of life, The Honest Broker challenges us all - scientists, politicians and citizens - to think carefully about how best science can contribute to policy-making and a healthy democracy.