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Whodunit?: Bringing justice with forensic linguistics

Today I am interviewing Joseph Devney, a forensic linguist in California.

Hello Joe. First of all, please tell us what a forensic linguist does. Frankly, when I hear the word "forensic", I tend to associate it with autopsies, fingerprints, and dental records. How does linguistics fit in with this?

Your first instinct is correct. The “forensic” part refers to examining evidence in an investigation. And that is the narrow meaning of the term: linguistic analysis of evidence in court or in a police investigation.

But it has a broader meaning that is a more accurate description of the breadth of the field. It covers the intersection of language and law. In fact, some people use the term “language and law” instead because it reflects this perspective better.

This broader definition is preferred in the field, because it includes the things that are actually discussed by researchers and practitioners. Not just evidence in trials, but things like jury instructions, detecting plagiarism, the strategies used in police interviews, and interpreting statutory language. Any situation in which language studies and the law intersect.

The International Association of Forensic Linguists has members who know about these areas and more. (

Do you work with the written or the spoken word? Which is more challenging to analyze and decode?

I came to linguistics from a career as a writer. So I am more comfortable with the written word. But I can work from recordings and transcripts. With recordings, of course, some words or even full sentences can be unclear. Still, if at all possible, I would want access to the original audio recording, rather than trusting that someone else’s transcript is accurate enough.

Linguists pay closer attention to the details of language use than most people. To a linguist, a pause, or a filler word like “um,” can be significant if I am performing discourse analysis. We want to make sure that those things are captured in the transcript. And that utterances that are unclear are noted in the transcript that way as well.

There is a sister discipline, though, called forensic phonetics. The study of phonetics is part of linguistics, but these people specialize in analyzing voices and speech and audio recordings rather than the written word. They know a lot about how the sounds of speech are formed in the vocal tract.

The forensic phoneticians have their own professional organization, the International Association for Forensic Phonetics and Acoustics. (

What are the areas of law you deal with?

Any case in which language evidence is involved. Well, language evidence that I think I can analyze and come to useful conclusions. I recently worked on a criminal case, analyzing both a short witness statement and a very long police interview.

Linguists also get involved in trademark disputes, copyright cases, and interpretations of contract language—areas with clear connections between language and law.

Who employs forensic linguists?

In most cases, forensic linguists have “regular” jobs (often as linguistics professors), and do consulting in this field. The linguists can help with investigations—narrowing down a list of suspects for the police, for example. Tim Grant of Aston University in the U.K. (who just finished his term as president of IAFL) helps train police so they will be better interviewers. (

The FBI has had its own linguistic profilers on staff. The first of these, James Fitzgerald, is the one who used language evidence to get the search warrant that led to the arrest of Ted Kaczynski, the “Unabomber,” back in the 1990s. He has left the FBI, and is one of several forensic linguists who work independently.

But the typical client is a lawyer who needs help on a particular case. The linguist will come in to analyze whatever language evidence is in dispute, written or spoken. Is this trademark really a common word? Does this statement that seems to amount to a confession really mean that in the larger context? Are these passages from different books similar enough that they amount to copyright infringement? Could this defendant have written the ransom note that the police claim he did? Was what the defendant said on a recorded phone call a business proposition or a disguised threat?

That brings up another question. If a lawyer hires a forensic linguist, doesn’t that mean the linguist is there to build the case the lawyer wants, so they will win? Could the linguist bias his or her analysis that way?

I have heard this question before. The answer is no, not if the linguist is ethical. And we do have a code of ethics to follow, published by the Linguistic Society of America. A linguist submitting a report to the court can reference this code of ethics in the report. It says, for example, that the linguist won’t take cases in which the fee is dependent on the lawyer winning the case.

As an expert witness, the linguist’s obligation is to the court, not to the lawyer paying the fee. We analyze the language evidence, and simply report what we find. It may turn out that I need to tell my client, the lawyer, “this document supports the other side’s case.” The lawyer then makes her own decision about whether to use my report in court. To avoid a conflict of interest, I get paid the same fee no matter what I find out from my analysis.

You can read the code of ethics here.

What is your strategy to cope with people who not only speak a different language, but also come from cultures that are radically different from ours? I'm thinking of Mexican indigenous migrants from places like Oaxaca.

This would be a difficult problem. I assume that is why you are asking. Clearly, I would not have the requisite background to interpret testimony from people who don’t speak English, and few people would know those languages. I would start contacting people in the broader community of linguists, and try to find a linguist—or possibly a sociologist—who has worked with this language or this ethnic group.

You work in the U.S., and have mentioned the U.K. Is forensic linguistics practiced in other parts of the world?

Oh, yes. This summer I attended a conference sponsored by the IAFL, and met people from around the world. A woman from Kenya has been researching the metaphors that are used to just barely disguise the hate speech that helped incite election-time violence there. A linguist in Brazil teaches hostage negotiators. One speaker talked about her research into the way that juveniles are treated in the justice system in the Netherlands. I learned about how the use of English in the courtroom affects the delivery of justice in Hong Kong.

It really is used worldwide.

What is corpus linguistics and how can it be used as a tool?

A corpus in this context is a large sample of language from the “real world.” (The plural is corpora.) Corpus linguistics is the practice of analyzing these corpora using software. There are a lot of ways that corpora can be used in the legal context.

Recently there was an opinion piece in the Washington Post about using corpus linguistics to find the everyday meaning of words that might be relevant in a particular case. ( The authors write, “When problems of ambiguity in legal language arise, we expect judges and lawyers to turn increasingly to data from linguistic databases and less to mere dictionaries.”