In 1962, the eminent statesman Dean Acheson enunciated a principle that has dominated global politics ever since: that no legal issue arises when the United States responds to a challenge to its 'power, position, and prestige'. In short, whatever the world may think, U.S. actions are legitimate because they say so.Spanning the impact of Edward Snowden's whistleblowing and Palestinian-Israeli relations to deeper reflections on political philosophy and the importance of a commons to democracy, Because We Say So takes American imperialism head on.