In 1996, Unabomber Ted Kaczynski was arrested after his writing style helped identify him. It would be the first time in history that text analysis evidence was used in U.S. federal courts, to obtain a search warrant. Since then, language has figured in to numerous criminal investigations. In the field known as “forensic linguistics,” things like word choice, spelling and punctuation can all serve as virtual fingerprints. And today emails, tweets, and texts give linguists a trove of lexical data to examine in criminal cases. But many experts remain skeptical that this kind of work has the scientific basis necessary for use in high-stakes cases. We explore linguistic evidence in court in the age of social media.