The long and tortured career of Ira B. Arnstein, "the unrivaled king of copyright infringement plaintiffs," opens a curious window into the evolution of copyright law in the United States. As Gary A. Rosen shows in this frequently funny and always entertaining history, the litigious Arnstein was a trenchant observer and most improbable participant in the transformation of not just copyright, but of American popular music itself. A musical prodigy...