Are scientific expert witnesses partisans, or spokesmen for objective science? This ambiguity has troubled the relations between scientists and the legal system for more than 200 years. Modern expert testimony first appeared in the late eighteenth century, and while its use steadily increased throughout the nineteenth century, in cases involving everything from patents to X-rays, the respect paid to it steadily declined, inside and outside of the courtroom. With deep learning and wry humor, Tal Golan tells stories of courtroom drama and confusion and media jeering on both sides of the Atlantic, until the start of the twenty-first century, as the courts still search for ways that will allow them to distinguish between good and bad science.