Study explains why laws are written in incomprehensible style

Legal documents are notoriously difficult to understand, even for lawyers. This raises the question: Why are these documents written in a style that makes them so impenetrable?

Cognitive scientists at MIT think they may have found the answer. Just as “magic spells” use special rhymes and archaic terms to signal their power, the convoluted language of legalese works to convey a sense of authority, they conclude.

In a study published in the Proceedings of the National Academy of SciencesResearchers have found that even non-lawyers use this type of language when asked to write laws.

“People seem to understand that there is an implicit rule that laws should be written this way, and they write them that way,” says Edward Gibson, professor of brain and cognitive sciences at MIT and lead author of the study.

Eric Martinez, Ph.D., is the lead author of the study. Francis Mollica, a professor at the University of Melbourne, is also an author of the study.

Cast a legal spell

Gibson’s research group has been studying the unique characteristics of legalese since 2020, when Martinez came to MIT after earning a law degree from Harvard Law School. In a 2022 study, Gibson, Martinez, and Mollica analyzed legal contracts totaling about 3.5 million words, comparing them to other types of writing, including film scripts, newspaper articles, and academic papers.

The analysis revealed that legal documents often feature lengthy definitions inserted in the middle of sentences, a feature known as “center-embedding.” Linguists have previously found that this type of structure can make text much more difficult to understand.

“Legal language has sort of developed this tendency to put structures inside other structures, in a way that’s not typical of human languages,” Gibson says.

In a follow-up study published in 2023, researchers found that legalese also made documents harder for lawyers to understand. Lawyers tended to prefer plain English versions of documents, and they felt those versions were just as applicable as traditional legal documents.

“Lawyers also find legalese unwieldy and complicated,” Gibson says. “Lawyers don’t like it, and laypeople don’t like it, so the goal of this article was to try to understand why they draft documents this way.”

Researchers have proposed several hypotheses to explain why legalese is so prevalent. One is the “copy-and-revise hypothesis,” which suggests that legal documents begin with a simple premise and then insert additional information and definitions into existing sentences, creating complex central clauses.

“We thought it was plausible that you could start with a simple first draft and then think about all the other conditions you want to include later. The idea is that once you start, it’s much easier to integrate it into the existing provision,” says Martinez, who is now a researcher and professor at the University of Chicago Law School.

The study’s results, however, led to another hypothesis, the so-called “magic formula” hypothesis. Just as magic formulas are written in a particular style that distinguishes them from everyday language, the convoluted style of legal language seems to signal a particular type of authority, the researchers say.

“In English culture, if you want to write something that’s a spell, people know the way to do it is to put a lot of old-fashioned rhymes in it. We think the central insertion is perhaps a way of signaling legalese in the same way,” Gibson says.

In the study, the researchers asked about 200 nonlawyers (native English speakers living in the United States, recruited through a crowdsourcing site called Prolific) to write two types of texts. In the first task, participants were asked to write laws prohibiting crimes such as drunk driving, burglary, arson, and drug trafficking. In the second task, they were asked to write stories about these crimes.

To test the copying and editing hypothesis, half of the participants were asked to add additional information after writing their initial law or story.

The researchers found that all subjects wrote laws with central clauses, whether they wrote the law all at once or were asked to write a rough draft and add to it later. Moreover, when they wrote stories related to these laws, they wrote them in much simpler English, whether or not they had to add information later.

“When they were writing laws, they did a lot of core integration, whether they had to amend them or write them from scratch. And in this narrative text, they didn’t use core integration in either case,” Martinez says.

In another set of experiments, about 80 participants were asked to write laws, along with descriptions that would explain those laws to visitors from another country. In these experiments, participants again used central embedding for their laws, but not for descriptions of those laws.

The origins of legal jargon

Gibson’s lab is currently studying the origins of the central insertion in legal documents. Early American laws were based on British law, so the researchers plan to analyze British laws to see if they exhibit the same type of grammatical construction. And going back much further, they plan to analyze whether the central insertion is found in the Code of Hammurabi, the oldest known set of laws, which dates to about 1750 B.C.

“It may be that there is simply a stylistic way of writing that dates from that time, and if it was considered successful, people would use it in other languages,” Gibson says. “I suspect it’s an accidental property of the way laws were first written, but we don’t know yet.”

The researchers hope that their work, which identified specific aspects of legal language that make it more difficult to understand, will motivate lawmakers to try to make laws more understandable.

Efforts to write legal documents in simpler language date back at least to the 1970s, when President Richard Nixon declared that federal regulations should be written in “plain language.” However, legal language has changed very little since that time.

“We’ve only very recently discovered what makes legal language so complicated, so I’m optimistic that it can be changed,” Gibson says.

This article is republished with kind permission from MIT News (web.mit.edu/newsoffice/), a popular site covering the latest research, innovation, and teaching at MIT.