A new study from MIT cognitive scientists has determined why legal documents are notoriously difficult for nonlawyers to understand.

The researchers compared thousands of legal contracts to other types of texts, including movie scripts, newspaper articles, and academic papers. Using a text analysis tool, they identified four patterns more common in legal documents: nonstandard capitalization (such as using all caps), use of passive voice, use of jargon, and the practice of inserting long definitions in the middle of sentences, known as “center-embedding.”

Then they asked nonlawyers to read either standard legal documents or documents in which one of the four legal text patterns was altered without changing the meaning. They found that the passive voice and nonstandard capitalization did not hinder readers. But using legal terms like “lessee” and “lessor” proved confusing; replacing them with more common alternatives like “tenant” and “landlord” improved readers’ ability to understand and recall the meaning of what they’d read. 

The main culprit of confusion, however, was center-embedding. Recall and understanding improved the most when center-embedded structures were replaced with more direct sentences, with terms defined separately.

For example, nonlawyers found things like this baffling: “In the event that any payment or benefit by the Company (all such payments and benefits, including the payments and benefits under Section 3(a) hereof, being hereinafter referred to as the ‘Total Payments’), would be subject to excise tax, then the cash severance payments shall be reduced.”

Replacing that center-embedded structure with separate, simple sentences defining terms helped: “In the event that any payment or benefit by the Company would be subject to excise tax, then the cash severance payments shall be reduced. All payments and benefits by the Company shall hereinafter be referred to as the ‘Total Payments.’ This includes the payments and benefits under Section 3(a) hereof.”

“Making legal language more straightforward would help people understand their rights and obligations better, and therefore be less susceptible to being unnecessarily punished or not being able to benefit from their entitled rights,” says study lead author Eric Martinez, a recent Harvard Law School graduate and licensed attorney who is now a graduate student in the lab of brain and cognitive sciences professor Edward Gibson, the paper’s senior author.