Forensic linguistics, which is sometimes referred to as forensic stylistics, is a branch of linguistics that focuses on taking the analytical techniques of that field and applying them to legal and criminal issues as far-ranging as trial, investigation, rehabilitation and punishment. As a discipline, forensic linguistics reviews spoken and written materials and, using the scientific techniques of linguistics, analyzes them. This branch of linguistics is concerned with such things as determining who authored a written document and identifying speakers of oral material, such as taped conversations. Forensic linguistics also measures as well as determines both the content and meaning of both spoken and written material.
In deciding authorship, the technique used in the field of forensic linguistics is to study a written communication and compare its spelling, grammar, vocabulary, tone and sentence structure to known writings from the suspect to determine whether he or she wrote it. An example might be a suicide note whose legitimacy is in question. This type of analysis is particularly useful in threat assessment, where a ransom note or a menacing email, letter or text message has been received. For example, in the case of threatened workplace or school violence, specific word usage can give law enforcement officials insight into how likely it is that action will follow.
These same forensic linguistic tools are useful in the investigation of false allegations as well as in analysis of statements and confessions. In those instances, forensic linguistic analysis is used to establish the truthfulness of the writer's or speaker’s words, the information that is conveyed by choice of words and the mention of any little-known information. By studying these things, forensic linguistics can suggest the most effective approach to take with an individual suspect, witness or victim.
An analysis of oral communications can also be done through the use of forensic linguistics. Forensic phonetics is a sub-field of forensic linguistics and deals with voice or speaker identification analysis. The tools used in this type of forensic linguistic analysis are not only the acoustical sounds of the voice but also special language-use patterns such as vocabulary, pronunciation and grammar, which can reveal a speaker’s national, regional and social background. In short, whether in written or oral communications, forensic linguistics develops a collection of markers that brands a specific speaker or writer as unique and, ultimately, establishes a kind of linguistic "fingerprint" that can be used to determine guilt or innocence.