What is Forensic Linguistics?
[This
material may be used for
educational or academic purposes if cited or referred to as:
Peter Tiersma, What is Forensic
Linguistics?, http://www.languageandlaw.org/FORENSIC.HTM]
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The field of forensic linguistics has been growing in prominence in the
past couple of decades. There is now a profession organization
that bears this title (the International Association of Forensic
Linguists), as well as the International Association of Forensic
Phoneticians, which is closely related. There is at least one
journal (the International Journal
of Speech, Language, and the Law), formerly known as Journal of Forensic Linguistics, and there
seem to be two or
three conferences a year devoted to the topic. Programs in
forensic linguistics are offered at several universities (mostly in the
United Kingdom), and there are online courses of study either in
existence or in the planning stages. Oddly, the scope of the term
"forensic linguistics" remains somewhat vague.
Criminal Cases
At least in the United States, the term
"forensic" (as in forensic science or forensic expert) refers most
prominently
to a person or methodolgy that helps solve crimes. Not
surprisingly, forensic laboratories are generally run by law
enforcement agencies.
For instance, the Vermont Forensic Laboratory does firearms and tool
mark analysis (which includes firearms examination, ammunition
examination, serial number restoration, toolmark comparison, etc.),
serology (dealing with DNA evidence), a photography section (doing
various photographic processing and analysis), a chemistry section
(paint and fire debris analysis), and a drug section that analyzes
substances thought to be drugs (see
http://170.222.24.9/cjs/lab.html). Virtually all laboratories of
this kind offer expert court testimony in their areas of expertise.
Consider also the description of the FBI
laboratory
on its website:
As
one of the largest and most
comprehensive forensic laboratories in the world, the FBI Laboratory
provides forensic and technical services to federal, state, and local
law enforcement agencies at no expense to these agencies. Analyses of
physical evidence ranging from blood and other biological materials to
explosives, drugs, and firearms are conducted by the Laboratory, which
also serves as a continual source of new scientific techniques.
Laboratory examiners provide expert witness testimony in court cases
regarding the results of forensic examinations, and specially-trained
teams of Special Agent and support personnel assist domestic and
international law enforcement agencies in large-scale investigations
and disasters.
(source:
http://www.fbi.gov/hq/lab/labhome.htm)
Similarly, in England the Forensic Science Service is a branch of the
UK Home Office. Its mission is to "meet the needs of specific
police investigations." It does so in the following ways:
- Property crime - providing support in
the investigation of burglary, fraud, robbery, fire investigation,
theft of vehicles and theft from vehicles offences.
- Serious crime - providing support in
the investigation of murder, suspicious death, sexual offences and
other serious offences against the person.
- Drugs - providing intelligence in the
investigation of a range of drug-related offences including supply,
possession, importation and exportation, production and cultivation.
- Road policing - providing support for
drink and drug driving offences and accident investigation.
- Organised crime - providing support to
police, HM Customs and Excise and the National Crime Squad including
investigation of terrorism.
- International crime - providing
support to the Foreign and Commonwealth Office, British Council and
overseas law enforcement agencies.
- Hi-tech crime - providing support in
the investigation of computer or electronic related crime and fraud.
- Commercial - providing drug-testing
facilities for prisons and offering a paternity testing service.
(source:
http://www.forensic.gov.uk/forensic_t/inside/about/index.htm)
To limit the forensic sciences to solving
crimes would be too narrow, however, because forensic expertise
can also be used by the defense in a criminal case. The defense
may be able to offer its own expert to counter evidence introduced by
the prosecution. Often such evidence is offered by independent
laboratories or individual experts. In that case, the evidence
usually does not solve a crime, but rather is offered to show that law
enforcement's proposed solution to the crime is wrong.
Forensic linguists are involved in many areas that relate to crime,
both solving crime and absolving people wrongly accused of committing
crimes. Some of these areas of research and expertise include:
- voice identification (for instance, determining whether the
voice on a threatening tape recording was that of the defendant;
sometimes also called forensic
phonetics)
- author identification (determining who wrote a particular
text by comparing it to known writing samples of a suspect; sometimes
also called forensic stylistics)
- discourse analysis (analyzing the structure of a writing or
spoken utterance, often coverly recorded, to help determine issues such
as who is introducing topics or whether a suspect is agreeing to engage
in a criminal conspiracy)
- linguistic proficiency (did a suspect understand the Miranda
warning or police caution?)
- dialectology (determining which dialect of a language a
person speaks, usually to show that a defendant has a different dialect
from that on an incriminating tape recording. As opposed to voice
identification, which analyzes the acoustic qualities
of the voice, dialectology uses linguistic features to accomplish
similar goals)
- "linguistic origin analysis" (this is my term for the
process of
trying to determine what a person's native language is, often for
purposes of granting or denying applications for political
asylum. A more common term is "language analysis," but that term
is overly broad, it seems to me. Note that linguistic origin
analysis is very similar to what we might call forensic dialectology)
- "linguistic veracity analysis" (again, I think I may have
invented this term, but it refers to various linguistically-inspired
methods for determining whether a speaker or writer was being truthful)
These areas of research have varying degrees of acceptability or
reliability within the field. Thus, voice identification, if done
by a qualified phonetician who understands the limitations of the
methodology and findings, is accepted as being relatively reliable
(although whether it meets evidentiary standards of the courts is
another issue, especially when the analysis is done by a technician
based on machine analysis of the voice). See Peter Tiersma and
Lawrence Solan, The Linguist on the
Witness Stand: Forensic Linguistics in American Courts, 78
Language 221-39 (2002).
Author identification is
a very interesting and potentially useful area, but it is hampered by
the fact that documents in a
forensic setting (ransom notes, threatening letters, etc.) are usually
much too short to make a reliable identification. Moreover, which
linguistic features are reliable indicators of authorship, and how
reliable those features are, remains to be discovered. Research
is ongoing, however, and the availability of large corpora of speech
and writing samples suggests that the field may advance in the future
(although the typically small size of the documents in most criminal
cases will
always be a problem). Moreover, it may be sufficiently reliable
to eliminate someone as an author, or select an author from a small
group of suspects.
Discourse analysis is a very broad field, and how acceptable its
conclusions are depends on the methodology that is used and how any
conclusions are described. Discourse analysist can provide
helpful information by close analysis of a covert recording and, for
instance, showing that the suspect's use of "I" rather than "we" might
indicate noncomplicity in a conspiracy. Linguists have also
pointed out that when a suspect is recorded as saying "yeah" or
"uh-huh" in response to a suggestion, the suspect is not necessarily
agreeing with the suggestion, but may simply be providing a feedback
marker to indicate he has understood the utterance, as we routinely do
in ordinary conversation. Courts have a mixed record in whether
they allow discourse analysists to testify as experts, but even when
not allowed to testify they may be useful to the lawyers in preparing a
case.
Proficiency testing
and dialectology are both time-tested and relatively noncontroversial
areas of linguistics. Of course, because of the influence of mass
media and population mobility, dialects are becoming less distinct than
they once were, and people often mix dialect features. This is a
serious problem with linguistic
origin analysis. Determining a person's origin by means of his or
her dialect or language is also complicated by the fact that many
languages straddle a border or are spoken in multiple countries.
It seems to me that in many cases it is possible to determine that a
person is not, based on his language, from a specified country (which
is usually critical to an asylum application), but such determinations
must be made carefully by well-qualified experts who understand
the limitations of the approach.
I am highly skeptical of efforts to determine, using linguistic
methologies (such as type/token rations), whether a speaker or writer
is being truthful. There are few, if any, reputable linguists who
claim that this is currently possible with any degree of accuracy.
Aside from veracity analysis, it seems to me that all of these
methodologies can play important roles in the criminal justice system,
although it may not always be in the form of testimony in the
courtroom. Where the question is if a suspect is the person
speaking on a tape, or whether a suspect wrote a particular threatening
note, or whether a person speaks the variety of English-based creole of
Sierra Leone (and not the type of creole spoken in Nigeria), a
well-trained linguist might be in a position to be of assistance to a
jury. A forensic linguist is often able to say with relative
confidence that it is not the
voice of person X on a tape recording, or that person Y most likely did
not author a particular
document. This is simply a binary choice. On the other
hand, it is far more problematic to say with sufficient reliability
that it is the voice of
person X or the writing of person Y, and not the voice or writing style
of some other possible person (in a case where there could be thousands
or even millions of other possible suspects).
Perhaps because it is much easier to eliminate someone as a suspect
with a reasonable degree of confidence than it is to prove him or her
guilty beyond a reasonable doubt, it is not surprising that most
linguistic expertise in criminal cases has been for the defense, where
reliability is less essential. Nonetheless, linguistic expertise
can be useful to the government as well, especially at the
investigatory stage. And because ongoing research is making
forensic linguistic approaches more reliable, the field may be
increasingly useful to investigators and prosecutors.
Interestingly, both Germany and the Netherlands have linguists working
for their criminal laboratories (the Bundeskriminalamt
in Germany, and the Nederlands
Forensisch Instituut in the Netherlands).
Civil
Cases
Although most forensic expertise does indeed relate to criminal law, it
seems to me that this characterization is also too narrow. Notice
that one of the things that the Forensic
Science Service does in the U.K. is to provide paternity testing
services (for a fee). The website specifically notes that the
services are available to lawyers. While paternity testing may
involve a crime, it is also used a great deal in civil cases.
Hence the adjective forensic can
apply to civil cases as well.
Thus, we can define forensic sciences more inclusively as encompassing
any branch of scientific or technical expertise that is useful in
deciding cases. It is important at this point to distinguish factual from legal issues. Judges and
lawyers are the experts on the law, so they will almost invariably
object if an expert in another field tries to opine on the meaning of a
statute or judicial opinion. On the other hand, it is
specifically the job of the jury (or, in a bench trial, of the judge)
to decide questions of fact. The role of experts in the legal
process is to assist the jury or judge (the "factfinder") to make all
factual determinations.
We have seen how forensic linguists can help make factual
determinations in the criminal law. Linguists can also make
similar contributions in civil cases. Although the use of the
term forensic linguist in
the context of criminal law is not particularly controversial, since
forensics is so closely tied to criminal law, the term is somewhat less
warmly embraced on the civil side, in my opinion. Linguists who
testify in civil cases tend to consider themselves ordinary academics
who hope their expertise can somehow be useful to the legal system, and
do not necessarily consider themselves experts in "forensic
linguistics." Others disagree and find the term
useful. My own view is that someone who comes into court as a
"linguist" may have somewhat greater credibility that someone who
claims to be a "forensic linguist," since the former term suggests
somewhat greater objectivity, and the latter suggests someone who is
trying to specialize in, or promote, legal consulting and who may
therefore be viewed somewhat more readily as a "hired gun."
Although I believe that linguists can sometimes play an important role
in helping a judge or jury decide both criminal and civil factual
issues, I do not consider myself to to be a forensic linguist. My
interest is in the intersection and interaction of language and
law. For my purposes, forensic linguistics, which strongly
suggests helping solve criminal cases, is just too limited a term for
what I do. In fact, I have tried to persuade the
International Association of Forensic Linguists to change its name to
something like International Language and Law Association, in the hope
of broadening the appeal of the association to people who do not
consider themselves to be forensic linguists. But my motion was
soundly defeated.
Nonetheless, forensic linguistics is an interesting and growing
specialty, especially in the UK. If you're interested in becoming
a forensic linguist, my advice is to concentrate first on becoming the
best linguist you can be. Then add the forensics.