It is a myth that texts, like Finns are silent -- but like Finns they don't tell their secrets to everyone. Among the tasks of the forensic linguist are: to discover what texts are actually saying, to teach texts to express themselves better, to interpret their meaning or highlight their significance for Courts of Law and to identify the voices of their author(s).
It is now some thirty years since Jan Svartvik published The Evans Statements: A case for forensic linguistics (Svartvik 1968). In his short monograph Svartvik demonstrated that the incriminating parts of a set of four linked statements, purportedly dictated by Timothy Evans to police officers, had a grammatical style measurably different from that of the uncontested parts of the statements. This marked the birth of a new discipline; initially, growth was slow. In unexpected places there appeared isolated articles in which the author, often a distinguished linguist, analysed a disputed confession or commented on the likely authenticity of purported verbatim records of interaction or showed why an accused could not be the person whose voice was recorded on an incriminating tape-recording or identified and evaluated inconsistencies in the language which had been attributed to non-native speakers (Levi 1994a).
In these early days there was, however, no attempt to establish a discipline nor even a methodology -- the work was usually undertaken as an intellectual challenge and almost always required the creation, rather than simply the application, of a method of analysis. In the past ten years, by contrast, there has been a rapid growth in the frequency with which Courts in a number of countries have called on the expertise of linguists; in consequence, methodology is developing rapidly and a growing number of linguists are acting as expert: witnesses, some even on a full time basis (see Levi 1994b; Eades 1994). Forensic linguistics has come of age and, like other mature areas of applied linguistics, is now beginning to raise new and exciting research questions for descriptive linguistics.
2. What do forensic linguists do?
Forensic linguists in the main set out to provide answers to three questions: what does a given text "say", what does it mean and who is its author? In answering these questions they draw on knowledge and techniques derived from one or more of the sub-areas of descriptive linguistics: phonetics and phonology; lexis, syntax, semantics and pragmatics; discourse and text analysis; computational and corpus linguistics.
2.1. What does a text say?
Tape-recordings of interviews, telephone calls and conversations, often of less than satisfactory quality, now constitue important evidence in a large number of criminal trials. The first thing the Court needs to know in such cases is what was actually said -- what was the locution -- before there can be any discussion of the illocutionary value. The forensic phonetician can play a crucial role by enhancing the tape quality and then decoding crucial indistinct words and phrases. For instance, as everyone knows, there can be surprisingly little difference auditorily, in fast conversational speech, between opposite polarity pairs like can and can't even when the sound quality is good -- when a recording is of poor quality the co-operative lay listener or transcriber, trying to make sense of jumbled sounds, may "hear" one thing, where the expert, with a trained ear and the help of sophisticated equipment, will perceive something entirely different. Just one example will suffice: a suspect accused of murder with a strong West Indian accent and some dialect features, was transcribed as saying, in an interview with police officers, that "he got on a train" and then "shot a man to kill"; the forensic phonetician was able to demonstrate that the accused actually said the innocuous and contextually much more plausible "showed a man ticket"! …