Within Legalese
Why One Legal Sentence Can Overload Memory
Clauses nested inside other clauses force readers to hold unfinished ideas in memory, slowing comprehension.
On this page
- How center embedding interrupts comprehension
- Examples that preserve meaning but read faster
- When qualifications belong outside the main clause
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Introduction
Centre-embedded clauses are one of the most reliable ways to make a legal sentence harder to read. They occur when a writer inserts a qualification, definition, exception, or subordinate clause into the middle of a sentence before the main idea has been completed. Readers must keep the unfinished sentence in mind while processing the interruption, then reconnect the pieces afterwards. In legal documents, where multiple qualifications are often inserted before the main verb or obligation appears, this structure can significantly slow comprehension and increase rereading. Research from MIT and psycholinguistics has identified centre embedding as a major contributor to the difficulty of legal language, not because the concepts are necessarily more complex, but because the sentence structure places unusually heavy demands on working memory. [MIT News+2DSpace]news.mit.edulegal writing understanding 0307MIT NewsObjection: No one can understand what you're saying7 Mar 2022 — “Using center-embedded clauses is standard writing practice in le…
For readers interested in increasing reading speed, centre embedding is important because it reveals a practical limit of fluent reading: speed falls when the brain must hold several unfinished ideas at once.
How Centre Embedding Interrupts Comprehension
A sentence normally becomes easier to process when readers can identify its subject, verb, and core action in sequence. Centre embedding disrupts that flow.
Consider a simple legal instruction:
The tenant must obtain written consent before subletting.
Now compare it with a centre-embedded version:
The tenant, except where otherwise permitted under Section 4 and subject to the landlord’s prior approval, which approval shall not be unreasonably withheld, must obtain written consent before subletting.
The legal meaning may be similar, but the reader cannot immediately connect “tenant” with “must obtain”. Instead, the mind must temporarily store the beginning of the sentence while processing intervening material.
Psycholinguists have long argued that centre-embedded structures are difficult because they require readers to maintain incomplete linguistic relationships in working memory. Each interruption increases the amount of information that must be retained until the sentence can be resolved. [PMC+2DSpace]pmc.ncbi.nlm.nih.govComputational principles of working memory in sentence…by RL Lewis · 2006 · Cited by 1118 — Our focus on the memory processes under…
This creates three specific problems:
- Delayed completion of the main thought. The reader encounters qualifications before discovering the sentence’s primary action.
- Memory competition. New information arrives before earlier information has been integrated.
- Relationship tracking. Readers must remember which exception, definition, or condition belongs to which part of the sentence.
The result is slower reading, greater cognitive effort, and a higher likelihood of losing track of the sentence’s structure. [MIT News+2MIT News]news.mit.edulegal writing understanding 0307MIT NewsObjection: No one can understand what you're saying7 Mar 2022 — “Using center-embedded clauses is standard writing practice in le…
Why Legal Documents Use It So Often
Legal drafting frequently inserts material into the middle of sentences because lawyers want qualifications to appear close to the words they modify. Definitions, exceptions, cross-references, and limiting conditions are often embedded directly into a clause rather than placed in separate sentences.
MIT researchers analysing legal documents found that centre-embedded constructions appear far more frequently in legal writing than in ordinary English. Their work identified long inserted definitions and qualifications as a distinctive feature of legalese. [MIT News]news.mit.edumit study explains laws incomprehensible writing style 0819MIT NewsMIT study explains why laws are written in an…19 Aug 2024 — legal documents frequently have long definitions inserted in the m…
From a drafting perspective, this can seem logical. Writers may believe that placing every qualification immediately beside the relevant term reduces ambiguity. The trade-off is that readers must process the qualification before they have fully understood the main proposition.
Why Memory Becomes the Bottleneck
The key mechanism is working memory: the limited mental workspace used to hold and manipulate information during comprehension.
When reading a centre-embedded sentence, the brain must retain unresolved elements while processing new material. For example, if a sentence begins with a subject and then introduces several embedded clauses, readers must remember the original subject until they finally encounter the main verb.
Linguistic research has repeatedly linked difficulty with centre embedding to these memory constraints. Sentences with multiple layers of embedding are often grammatically correct but difficult to understand because readers must store several incomplete relationships simultaneously. [Wikipedia+2PMC]WikipediaCenter embeddingCenter embedding
A classic illustration is:
The man that the woman that the child knew loved smiled.
The sentence is grammatical, but many readers struggle because they must keep track of several nested relationships before reaching the main action. Additional layers rapidly become difficult even for highly educated readers. [Wikipedia]WikipediaCenter embeddingCenter embedding
Legal documents often create a milder version of the same problem. Instead of nesting multiple relative clauses, they insert definitions, exceptions, and references into the centre of otherwise straightforward obligations. The memory burden is lower than in extreme linguistic examples but remains substantial enough to slow reading. [MIT News]news.mit.edumit study explains laws incomprehensible writing style 0819MIT NewsMIT study explains why laws are written in an…19 Aug 2024 — legal documents frequently have long definitions inserted in the m…
Examples That Preserve Meaning but Read Faster
One reason centre embedding attracts attention from plain-language advocates is that the legal meaning can often be preserved while reducing memory load.
Consider this version:
The purchaser, except where otherwise agreed in writing by the seller, whose consent may be withheld in accordance with Section 8, shall pay all transport costs.
A reader must suspend the main obligation while processing the qualification.
A less memory-intensive version might be:
The purchaser shall pay all transport costs. The seller and purchaser may agree otherwise in writing. Any decision to withhold consent is governed by Section 8.
The qualifications remain, but the main obligation becomes immediately visible.
The same principle applies to definitions:
Centre-embedded version
The employee shall return all Confidential Information, meaning information designated confidential or reasonably understood to be confidential, upon termination.
Reorganised version
Upon termination, the employee shall return all Confidential Information. Confidential Information includes information designated confidential and information that would reasonably be understood as confidential.
The legal content is substantially similar, but readers no longer have to interrupt one idea to process another.
Research comparing traditional legal drafting with simplified alternatives found that both lawyers and non-lawyers understood and recalled information more effectively when unnecessary complexity was removed. Lawyers also rated simplified versions as easier to understand without viewing them as less enforceable. [PNAS+2PubMed]pnas.orgEven lawyers do not like legaleseby E Martínez · 2023 · Cited by 24 — Experiment 1 revealed that lawyers, like laypeople, were less a…
When Qualifications Belong Outside the Main Clause
Not every qualification should be removed from a sentence. Some conditions are so central that separating them would obscure their connection to the main rule.
The challenge is deciding which information readers need immediately and which information can be postponed.
Qualifications are often better moved outside the main clause when they:
- Explain a term rather than determine the core obligation.
- Provide background detail.
- Reference another section for supplementary rules.
- Describe exceptions that apply only in uncommon circumstances.
- Define concepts that can be stated separately without altering meaning.
By contrast, a condition that fundamentally changes the obligation may need to remain closely connected to it.
The practical goal is not to eliminate qualification but to avoid forcing readers to hold too many unfinished ideas simultaneously. In many cases, placing the core rule first and moving supporting material afterwards allows readers to build understanding incrementally rather than reconstructing it retrospectively.
What This Means for Reading Speed
Centre-embedded clauses illustrate an important distinction between word difficulty and structural difficulty. A sentence can contain familiar vocabulary and still be hard to read if its structure overloads working memory.
For readers, recognising centre embedding helps explain why some legal passages feel unusually slow. The slowdown is not necessarily a failure of concentration or vocabulary knowledge. Often the sentence itself requires the reader to keep multiple unresolved pieces of information active at once. [MIT News+2DSpace]news.mit.edulegal writing understanding 0307MIT NewsObjection: No one can understand what you're saying7 Mar 2022 — “Using center-embedded clauses is standard writing practice in le…
For writers seeking clearer legal communication, the lesson is equally important. When qualifications, definitions, and exceptions are moved to the edges of sentences or broken into separate statements, readers can grasp the main idea sooner, retain more of what they read, and progress through the document with fewer pauses. Research suggests that this improvement benefits experts and non-experts alike. [PNAS+2MIT Brain and Cognitive Sciences]pnas.orgEven lawyers do not like legaleseby E Martínez · 2023 · Cited by 24 — Experiment 1 revealed that lawyers, like laypeople, were less a…
Amazon book picks
Further Reading
Books and field guides related to Why One Legal Sentence Can Overload Memory. Use these as the next step if you want deeper reading beyond the article.
Legal Writing in Plain English, Third Edition
Directly addresses legal readability, sentence structure, clarity, and reducing unnecessary complexity in legal prose.
Thinking, Fast and Slow
Explains cognitive load and mental processing limits that help readers understand why dense, interrupted sentences are harder to comprehend.
Plain English for lawyers
First published 1978. Subjects: Legal composition, English language, dictionaries, Law, dictionaries, Law, terminology, Kf250 .w9 2005.
Clarity for Lawyers: Effective Legal Language
Specifically addresses misunderstandings caused by legal drafting choices and shows how to make legal text easier to process.
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Endnotes
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Source: news.mit.edu
Title: legal writing understanding 0307
Link: https://news.mit.edu/2022/legal-writing-understanding-0307Source snippet
MIT NewsObjection: No one can understand what you're saying7 Mar 2022 — “Using center-embedded clauses is standard writing [practice]({{ 'practice/' | relative_url }}) in le...
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Source: dspace.mit.edu
Link: https://dspace.mit.edu/bitstream/handle/1721.1/148805/1-s2.0-S0010027722000580-main.pdf?isAllowed=y&sequence=2Source snippet
writing, not specialized concepts, drives processing...by E Martínez · 2022 · Cited by 87 — center-embedded clauses are difficult to pro...
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Source: news.mit.edu
Title: mit study explains laws incomprehensible writing style 0819
Link: https://news.mit.edu/2024/mit-study-explains-laws-incomprehensible-writing-style-0819Source snippet
MIT NewsMIT study explains why laws are written in an...19 Aug 2024 — legal documents frequently have long definitions inserted in the m...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC2239011/Source snippet
Computational principles of working memory in sentence...by RL Lewis · 2006 · Cited by 1118 — Our focus on the memory processes under...
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Source: Wikipedia
Title: Center embedding
Link: https://en.wikipedia.org/wiki/Center_embedding -
Source: pnas.org
Link: https://www.pnas.org/doi/10.1073/pnas.2302672120Source snippet
Even lawyers do not like legaleseby E Martínez · 2023 · Cited by 24 — Experiment 1 revealed that lawyers, like laypeople, were less a...
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Source: bcs.mit.edu
Title: even lawyers dont legalese
Link: https://bcs.mit.edu/news/even-lawyers-dont-legaleseSource snippet
MIT Brain and Cognitive SciencesEven lawyers don't like legalese29 May 2023 — A new study shows lawyers find simplified legal documents e...
Published: May 2023
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Source: pubmed.ncbi.nlm.nih.gov
Link: https://pubmed.ncbi.nlm.nih.gov/37253008/Source snippet
lawyers do not like legaleseby E Martínez · 2023 · Cited by 24 — Experiment 1 revealed that lawyers, like laypeople, were less able to re...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC10078164/Source snippet
In... The matrix verb as a source of comprehension difficulty in object relative...Read more...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC7226570/Source snippet
Comprehension of Relative Clauses and Center...by KH Cheon · 2020 · Cited by 5 — Our study provides a valuable insight into how the pure...
Additional References
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Source: johnjohnw.github.io
Link: https://johnjohnw.github.io/center_embedding_in_legalese/Source snippet
Center Embedding in LegaleseCenter embedding occurs when a sentence contains a clause within another clause. This syntactic complexity si...
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Source: reddit.com
Link: https://www.reddit.com/r/science/comments/1exa6as/mit_study_explains_why_laws_are_written_in_an/Source snippet
MIT study explains why laws are written in an...The convoluted “legalese” used in legal documents helps lawyers convey a special sense o...
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Source: adamsdrafting.com
Link: https://www.adamsdrafting.com/lawyer-attitudes-to-contracts-legalese-my-critique-of-a-new-study-featured-in-the-economist/Source snippet
Lawyer Attitudes to Contracts Legalese: My Critique of a...19 Jun 2023 — The false comparison between legal gibberish and more conventio...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/23190459_Complex_Sentence_Comprehension_and_Working_Memory_in_Children_With_Specific_Language_ImpairmentSource snippet
2002; 23:247–268. Roberts R, Gibson E. Individual differences in sentence memory. Journal of Psycholinguistic. Research. 2002...Read more...
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Source: ssl2.cms.fu-berlin.de
Link: https://ssl2.cms.fu-berlin.de/geisteswissenschaften/v/brainlang/PM_Intranet/Neurobiology-of-Language/Caplan2016HBNBL_workingmemorysentencecomprehension.pdfSource snippet
12. It was the... Memory and levels of proces- · sing in a psycholinguistic context. Journal of...Read more...
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Source: facebook.com
Title: lawyers and nonlawyers alike prefer contracts written in plain english
Link: https://www.facebook.com/ScientificAmerican/posts/lawyers-and-nonlawyers-alike-prefer-contracts-written-in-plain-english/679480314050244/Source snippet
Lawyers and nonlawyers alike prefer contracts written in...In a follow-up study published in 2023, the researchers found that legalese a...
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Source: adamsdrafting.com
Title: another misleading attempt to explain why legalese is the way it is
Link: https://www.adamsdrafting.com/another-misleading-attempt-to-explain-why-legalese-is-the-way-it-is/Source snippet
Another Misleading Attempt to Explain Why Legalese Is the...26 Aug 2024 — The first article offers as an example of center-embedded clau...
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Source: capstan.be
Link: https://www.capstan.be/research-by-mit-cognitive-scientists-sheds-light-on-the-features-that-make-legalese-so-difficult-to-understand-for-lay-people/Source snippet
23 Nov 2022 — Their research has pinpointed several features that distinguish legal from nonlegal texts, including center-embedded...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/6575933_Relational_processing_and_working_memory_capacity_in_comprehension_of_relative_clause_sentencesSource snippet
sing of subject-and object-relative clauses has been conducted on typically...Read more...
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Source: centaur.reading.ac.uk
Title: reading.ac.uk Working memory and L2 sentence processing
Link: https://centaur.reading.ac.uk/106198/1/Working%20Memory%20and%20L2%20Sentence%20Processing%20-%20Final.pdfSource snippet
memory and L2 sentence processing - CentAURby I Cunnings · 2022 · Cited by 11 — This includes both the tasks used to [measure]({{ 'measure/' | relative_url }}) memory capac...
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