A gripping intellectual history reveals how conservative justice Oliver Wendell Holmes became a free speech advocate and established the modern understanding of the First Amendment The right to express one's political views seems an indisputable part of American life. After all, the First Amendment proudly proclaims that Congress can make no law abridging the freedom of speech. But well into the twentieth century, that right was still an unfulfilled promise, with Americans regularly imprisoned merely for protesting government policies. Indeed, our current understanding of free speech comes less from the First Amendment itself than from a most unlikely man: the Supreme Court justice Oliver Wendell Holmes. A lifelong conservative, Holmes disdained all individual rights. Yet in 1919, it was Holmes who wrote a court opinion that became a canonical statement for free speech as we know it. Why did Holmes change his mind? That question has puzzled historians for almost a century. Now, with the aid of newly discovered letters and memos, law professor Thomas Healy reconstructs in vivid detail Holmes's journey from free speech skeptic to First Amendment hero. It is the story of a remarkable behind-the-scenes campaign by a group of progressives to bring a legal icon around to their way of thinkingand a deeply touching human narrative of an old man saved from loneliness and despair by a few unlikely young friends. Beautifully written and exhaustively researched, The Great Dissentis intellectual history at its best, revealing how free debate can alter the life of a man and the legal landscape of an entire nation.