Perhaps 25% of the cases I handle involve the authorship of anonymous, disputed, or forged documents. The client wants to know who’s writing those nasty, threatening emails or letters. I typically ask the client for writing samples from the suspected author. Sometimes there’s more than one suspect, and I have to decide which of them may be the author of the anonymous document(s).
Roger Shuy, one of the most preeminent forensic linguists, notes that the interpretation and application of the law are overwhelmingly about language. Thus, there are many situations in which the expertise of a linguist – someone trained in the precise description and analysis of language (but not necessarily a person who knows many languages) – can make substantial contributions to a case. The linguist can provide evidence one way or the other. Or he/she can clarify the linguistic principles, problems, and processes that the case involves.