Forensic linguistics

Forensic linguistics is the study, analysis and measurement of language in the context of crime, judicial procedure, or disputes in law, including the preparation and giving of written and oral evidence. It is a branch of applied linguistics.

Areas of study

The range of topics within forensic linguistics is diverse, but research occurs in the following areas:

The language of legal texts

The study of the language of legal texts encompasses a wide range of forensic texts, that is, text types and forms of analysis. Any text or item of spoken language can potentially be a forensic text, as long as it is somehow implicated in a legal or criminal context. This includes analysing the linguistics of documents as diverse as Acts of Parliament (or other law-making body), private wills, court judgements and summonses and the statutes of other bodies, such as States and government departments. One important area is that of the transformative effect of Norman French and Ecclesiastic Latin on the development of the English common law, and the evolution of the legal specifics associated with it. It can also refer to the ongoing attempts at making legal language more comprehensible to laypeople.

The language of legal processes

Amongst other things, this area examines language as it is used in cross-examination, evidence presentation, judge's direction, police cautions, police testimonies in court, summing up to a jury, interview techniques, the questioning process in court and in other areas such as police interviews.

Use of linguistic evidence in legal proceedings

These areas of research have varying degrees of acceptability or reliability within the field. Linguists have provided evidence in:

• Trademark and other intellectual property disputes
• Disputes of meaning and use
• Author identification (determining who wrote an anonymous texts by making comparisons to known writing samples of a suspect) (such as threat letters, mobile phone texts, emails)
• Forensic stylistics (identifying cases of plagiarism)
• Voice identification, also known as forensic phonetics, used to determine, through acoustic qualities, if the voice on a tape recorder is that of the defendant)
• Discourse analysis (the analysis of the structure of written or spoken utterance to determine who is introducing topics or whether a suspect is agreeing to engage in criminal conspiracy)
• Language analysis (forensic dialectology ) tracing the linguistic history of asylum seekers
• Reconstruction of mobile phone text conversations

Specialist databases of language (called corpora) are now frequently being used by forensic linguists. These include corpora of suicide notes, mobile phone texts, police statements, police interview records and witness statements.

Author identification

The identification of whether a given individual said or wrote something relies on analysis of their idiolect, or particular patterns of language use (vocabulary, collocations, pronunciation, spelling, grammar, etc). The idiolect is a theoretical construct based on the idea that there is linguistic variation at the group level and hence there may also be linguistic variation at the individual level. As the well-respected variationist William Labov pointed out thirty years ago, nobody has yet found "homogenous data" in idiolects. There are many reasons why it is difficult to provide such evidence. Firstly, language is not an inherited property, but one which is socially acquired . The acquisition process is continuous throughout life. Thus, an individual's use of language is always susceptible to variation from a variety of sources, including other speakers, the media and macro-social changes. Education can have a profoundly homogenizing effect on language use. Research into authorship identification is ongoing. The term authorship attribution is now felt to be too deterministic.

The small size of the documents (ransom notes, threatening letters, etc) in most criminal cases in a forensic setting is usually much too short to make a reliable identification. However, the information provided may be adequate to eliminate a suspect as an author or narrow down an author from a small group of suspects.

Authorship measures that analysts use include word length average, average number of syllabus per word, article frequency, type-token ratio, punctuation (both in terms of overall density and syntactic boundaries) and the measurements of hapax legomena (unique words in a text). Statistical approaches include factor analysis, Bayesian statistics, Poisson distributions, multivariate analysis, and discriminant function analysis of function word.

The Cusum (Cumulative Sum) method for text analysis has also been developed.. Cusum analysis works even on short texts and relies on the assumption that each speaker has a unique set of habits, thus rendering no significant difference between their speech and writing. Speakers tend to utilize two to three letter words in a sentence and their utterances tend to include vowel-initial words. In order to carry out Cusum test on habits of utilizing two to three letter words and vowel-initial words in a sentential clause, the occurrences of each type of word in the text must be identified and the distribution plotted in each sentence. The Cusum distribution for these two habits will be compared with the average sentence length of the text. The two sets of values should track each other. Any altered section of the text would show a distinct discrepancy between the values of the two reference points. The tampered section will exhibit a different pattern from the rest of the text.

Forensic stylistics

This discipline subjects written or spoken materials (or both), to scientific analysis for determination and measurement of content, meaning, speaker identification, or determination of authorship, in identifying plagiarism.

One of the earliest cases where forensic stylistics was used to detect plagiarism was the case of Helen Keller's short story. The blind American author was accused of plagiarism in 1892 with regard to her published short story, The Frost King. Upon investigation, The Frost King was found to have been plagarised from Margaret Canby's book Frost Fairies which had been read to her some time ago. Keller was discovered to have made only minute changes to common words and phrases and used less common words to put the same point across. She used 'vast wealth' instead of 'treasure' (approximately 230 times less common in the language) 'bethought' instead of 'concluded' (approximately 450 times less common), 'blade them' instead of 'told them' (approximately 30 times less common).

Derek Bentley

Forensic linguistics contributed to the overturning of Derek Bentley's conviction for murder in 1998 although there were other non-linguistic issues.

Nineteen-year-old Bentley was hanged in 1953 for his part in the murder of PC Sidney Miles. The fatal shot had been fired by Bentley's sixteen-year-old friend, Christopher Craig, when Bentley was already in police custody. Bentley, who had a mental age of eleven and was functionally illiterate, was convicted partly on the basis of his statement to police, allegedly transcribed verbatim from a spoken monologue.

Linguist Malcolm Coulthard examined the text when the case was reopened, and found a number of features which indicated police co-authorship, and which suggested that at least part of the statement resulted from questions and answers, as Bentley claimed, and was not, as police claimed, a "verbatim record of dictated monologue". One such feature was the use of the word "then", which Coulthard and his colleague David Woolls found to be the eighth most frequently-occurring word in Bentley's text, as compared with the 58th most frequent word in spoken English, and the 83rd most frequent word in English in general (according to the 1.5-million-word Bank of English corpus they were using). Feeling that the use of that word could be expected to be higher than average in witness statements (which generally report a sequence of events and show concern for accuracy about time), two corpora were compiled, one of witness statements and one of police statements. The word "then" occurred once every 930 words in the former but once every 78 words in the latter. Compared with the Bank of English corpus where it occurred once every 500 words, it occurred once every 53 words in Bentley's text. Coulthard's analysis of the statement was a major factor in Bentley's posthumous pardon. Coulthard's approach is not only a forensic discourse analysis but a combination of insights from different linguistic fields including speech act theory, corpus linguistics, register and even psycholinguistics.

The focus then turned to the use of the word "then". The frequent post-positioning of temporal (time-related) "then" after the grammatical subject ("I then" rather than "then I"), which occurred 7 times in the 582-word text, was also noted. The Bank of English spoken corpus showed "then I" to occur ten times more frequently than "I then", the latter occurring only once every 165,000 words. That structure did not occur at all in the corpus of witness statements but occurred once every 119 words in the corpus of police statements.

These features, combined with many others, contributed to a successful argument that the Bentley "confession" was, in part, the written work of police officers, and not simply a word-for-word transcript of Bentley's spoken statement as the police alleged.

The "Unabomber"

In the case of Theodore Kaczynski, who was eventually convicted of being the "Unabomber", family members recognized his writing style from the published 35,000-word Industrial Society and Its Future (commonly called the "Unabomber Manifesto"), and notified the authorities. FBI agents searching Kaczynski's hut found hundreds of documents written by Kaczynski, but not published anywhere. An analysis produced by FBI Supervisory Special Agent James R. Fitzgerald identified numerous lexical items and phrases common to the two documents. Some were more distinctive than others, but the prosecution (assisted by Vassar Professor of English Donald Foster) successfully argued that even the more common words and phrases being used by Kaczynski became distinctive when used in combination with each other.

Julie Turner

Julie Turner, a 40 year old woman living in Yorkshire, went missing one summer evening in 2005. Relatives became concerned when she did not return after an appointment with a male friend. She was reported missing on 8 June 2005 and the following afternoon her partner received this mobile phone text: "Stopping at jills, back later need to sort my head out". Two days after Julie went missing another text was received: "Tell kids not to worry. sorting my life out. (sic) be in touch to get some things". Her partner thought it was odd that she had not contacted the children. Police interviewed Howard Simmerson, a male friend, at his place of work on 10 June 2005. He denied any knowledge of her whereabouts.

After analysis of many hours of close circuit television footage police observed Simmerson driving a four-wheel drive vehicle with a barrel secured to the rear of the vehicle. Similar references in letters Simmerson had written to the language of the mobile phone texts were found, as well as several unusual orthographic and punctuation features. Olsson suggested to police that this evidence indicated a possibility of Simmerson being aware of the contents of the text messages. On being confronted with this intelligence Simmerson admitted that Julie, who was actually his lover, had been in his vehicle but claimed that she had opened his glove compartment and found a weapon in there with which she had accidentally shot herself. Her body was in the barrel that had been on the back of his four-wheel drive vehicle. Police eventually found the barrel and recovered the body. Simmerson was found guilty of Turner's murder at Sheffield Crown Court on 8 November 2005. He was sentenced to life imprisonment by Justice Pitcher.

Other

Forensic linguist John Olsson gave evidence in a murder trial on the meaning of 'jooking' in connection with a stabbing.

During the appeal against the conviction of the Bridgewater Four, the forensic linguist examined the written confession of Patrick Molloy, one of the defendants — a confession which he had retracted immediately — and a written record of an interview which the police claimed took place immediately before the confession was dictated. Molloy denied that the interview had ever taken place, and the analysis indicated that the answers in the interview were not consistent with the questions being asked. The linguist came to the conclusion that the interview had been fabricated by police. Later the conviction against the Bridgewater Four was quashed before the linguist in the case Malcolm Coulthard could produce his evidence.

In an Australian case reported by Eagleson, a "farewell letter" had apparently been written by a woman prior to her disappearance. The letter was compared with a sample of her previous writing and that of her husband. Eagleson came to the conclusion that the letter had been written by the husband of the missing woman, who subsequently confessed to having written it and to having killed his wife. The features analysed included sentence breaks, marked themes, and deletion of prepositions.

Dialectology was also used during the investigations into the Yorkshire Ripper tape hoax.

See also

• The International Association of Forensic Linguists (IAFL)
• Stylometry (authorship analysis)
• Writeprint

Further reading

• Gibbons, John (2003). "Forensic Linguistics: an introduction to language in the Justice System". Blackwell.
• Gibbons, John, V Prakasam, K V Tirumalesh, and H Nagarajan (Eds) (2004). "Language in the Law". New Delhi: Orient Longman.
• Gibbons, John, and M. Teresa Turell (eds) (2008). "Dimensions of Forensic Linguistics". Amsterdam: John Benjamins.
• Olsson, John (2008). "Forensic Linguistics", Second Edition. London: Continuum.
• Shuy, Roger W (2001). "Discourse Analysis in the Legal Context." In The Handbook of Discourse Analysis. Eds. Deborah Schiffrin, Deborah Tannen, and Heidi E. Hamilton. Oxford: Blackwell Publishing. pp. 437–452.

References

• Coulthard, R.M. (2000). "Whose text is it? On the linguistic investigation of authorship", in S. Sarangi and R.M. Coulthard: Discourse and Social Life, London, Longman.
• Coulthard, R.M., and A. Johnson (2007). "An Introduction of Forensic Linguistics: Language in Evidence" London and New York, Routledge.
• Eagleson, R. (2004). "Forensic analysis of personal written texts: a case study" in J Gibbons (ed.): Language and the Law. London, Longman, pp. 362–373.
• Grant, T. (2008). "Quantifying evidence in forensic authorship analysis", Journal of Speech, Language and the Law 14(1).
• Labov, W. (1972). Sociolinguistic patterns. Philadelphia, PA: University of Pennsylvania Press
• Miller, C. (1984). Genre as social action. Quarterly Journal of Speech, 70.
• Morton,A.Q., and S.Michaelson (1990). The Qsum Plot. Internal Report CSR-3-90, Department of Computer Science, University of Edinburgh.
• Tiersma, P. (1994). What is Forensic Linguistics?, http://www.languageandlaw.org/FORENSIC.HTM
• Olsson, J. (2004). Forensic Linguistics: An Introduction to Language, Crime and the Law. London: Continuum
• Olsson, J (2008). "Forensic Linguistics", Second Edition. London: Continuum.

External links

• ALIAS Technology LLC
• Forensic Linguistics at All About Forensic Science.com
• Cardiff University's MA (or Postgraduate Diploma/Certificate) in Forensic Linguistics
• Unabomber Case and Trial
• International Journal of Speech Language and the Law
• Forensic Linguistics Casebook - an independent wiki collecting cases where forensic linguistics has been used.
• Aston University's Centre for Forensic Linguistics
• International Summer School in Forensic Linguistic Analysis
• Hofstra University's Forensic Linguistics Project
• International Association of Forensic Linguists
• International Association for Forensic Phonetics and Acoustics
• Tiersma, Peter,: Homepage of eminent forensic linguist from Loyola Law School
• Institute for Linguistic Evidence, a nonprofit research organization.
• Language in the Judicial Process, edited by Bethany K. Dumas.
• Reading between the lines - BBC News article on the Centre for Forensic Linguistics
• Foulkes, Dr Paul, a forensic linguist at the University of York- Radio interview.
• Shuy, Roger W.: Homepage of eminent scholar in the field of language and law
• Forensic Linguistics Institute
• Butters, Ronald: Homepage of Professor, scholar, & journal editor in forensic linguistics
• Webcast of a lecture on forensic linguistics given by Roger W. Shuy at the University of Montana School of Law
• Webster’s forensic linguistic home page - links to a wide variety of forensic linguistic [resources
• Forensic Linguistics: Linguist as detective & expert witness - Public lecture by Prof. Malcolm Coulthard