On November 3, 1870, on a San Francisco ferry, Laura Fair shot a bullet into the heart of her married lover, A. P. Crittenden. Throughout her two murder trials, Fair's lawyers, supported by expert testimony from physicians, claimed that the shooting was the result of temporary insanity caused by a severely painful menstrual cycle. The first jury disregarded such testimony, choosing instead to focus on Fair's disreputable character. In the second trial,...