Solicitation to murder, bribery, threatening, extortion, perjury – all these are criminal acts whose medium is language. Since the 1970s American law enforcement agencies have been covertly tape recording conversations to bring such crimes to justice. With increasing frequency the decision of the court has come to turn on this taped evidence – and on unravelling the ambiguity and misunderstanding such evidence brings. Language Crimes tells the story of some of the remarkable cases in which Roger Shuy, as a linguist, has served as an expert witness. They include the trial of automobile executive John DeLorean and the U. S. Senate hearing concerning disciplinary action to be taken against Senator Harrison A Williams in the wake of the FBI's Abscam operation, as well as the cases of lesser known, average Americans, including a San Jose jeweller, a Honolulu union representative, a Kansas City lawyer and two Nevada brothel commissioners. These are intriguing stories which show the power of the study of language to assist the courts to achieve justice.