3 Must-Know Comma Rules for Lawyers

Comma Rules

Though we may be hired to interpret and apply the law, our clients rely on our writing skills to accurately capture their intent. It’s irresponsible to discount punctuation rules as pedantic and useless. Lawyers must get three comma rules right:

  1. Never use commas with restrictive modifiers.
  2. Always use commas with non-restrictive modifiers.
  3. Consistently use commas before the final item in a series.

The loose rules we used in college aren’t enough for the legal work we do now. Inconsistent or incorrect use of commas in these three areas can cause confusion and ambiguity—and cost your clients. Until you’ve memorized these comma rules and can apply them consistently, look them up every time you write.

What Are You Qualifying or Explaining?

A modifier can be a word or clause that describes, qualifies, or explains an element in a sentence. Our understanding of whether a modifier is restrictive or non-restrictive depends primarily on comma placement and the choice between that and which.

If you must identify a specific person, place, or thing—and distinguish it from other persons, places, or things—use a restrictive modifier. Use that without commas to show a restrictive modifier.

If you’re adding extra information and it is clear what the word or clause modifies and it is unnecessary to distinguish the people, places, or things that are modified, then use a non-restrictive modifier. Use which along with a comma to show a non-restrictive modifier.

Though some writers always use which and rely on the absence or presence of a comma to indicate whether the modifier is restrictive or non-restrictive, legal writers should follow the traditional rule to use that without commas for restrictive modifiers and which with commas for non-restrictive modifiers.

Here are your comma rules to remember:

1. Do Not Use Commas with Restrictive Modifiers

Never use commas to set off a restrictive modifier from the rest of the sentence. If a restrictive modifier is in the middle of a sentence, do not set it off with commas. For a stronger break in either position, use dashes.

2. Always Use Commas for Non-Restrictive Modifiers

If the non-restrictive modifier is at the end of the sentence, insert a comma to set off the modifier from the rest of the sentence. If a non-restrictive modifier is in the middle of a sentence, enclose it within a pair of commas.

For further reading on that, which, and restrictive and non-restrictive modifiers, check out 12.43-12.56 in A Manual of Style for Contract Drafting by WordRake user Ken Adams.

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Who Cares About the Oxford Comma?

The simple series rule is: Use commas to separate items in a series of three or more items. If the items in the series contain commas, then use semi-colons to separate the items. But what about the “Oxford” comma?

Grammar snobs on social media love to talk about this punctuation mark. But it’s not a special character, it’s a specific use of an existing character: the comma. In a series of three or more, the comma that follows the penultimate item and directly precedes and is called the Oxford or serial comma. Use of the Oxford comma is mostly a matter of preference and varies by region and profession.

Lawyers should use the Oxford comma to help avoid ambiguity. Three ambiguities may arise without this comma:

  • Whether the two final items in a list are one combined element or separate
  • Whether one noun phrase modifies the others when there are two or more noun phrases next to each other in a list
  • Whether a prepositional phrase modifies an item in a list

Here’s your rule to remember:

3. Consistently Use the Oxford Comma Before And and the Final Item

Rigorously follow your firm’s style guidelines on the Oxford comma. Usually, the Oxford comma is the safest way to avoid ambiguity, though there are no guarantees. But inconsistent use in a single document or across multiple documents invites litigation—so avoid it.

For further reading on the Oxford comma, check out 12.57-12.76 in A Manual of Style for Contract Drafting.


Inconsistent use of commas with modifiers or in series can lead to unintended and detrimental interpretations. For best results in your legal writing, learn these three comma rules. If you’d like to review the basic comma usage rules, check out our writing tip and sign up to receive a tip from legal writing expert and WordRake founder Gary Kinder every week in your inbox.

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About the Author

Ivy B. Grey is the Chief Strategy & Growth Officer for WordRake. Prior to joining the team, she practiced bankruptcy law for ten years. In 2020, Ivy was recognized as an Influential Woman in Legal Tech by ILTA. She has also been recognized as a Fastcase 50 Honoree and included in the Women of Legal Tech list by the ABA Legal Technology Resource Center. Follow Ivy on Twitter @IvyBGrey or connect with her on LinkedIn.

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Our Story

WordRake founder Gary Kinder has taught over 1,000 writing programs for AMLAW 100 firms, Fortune 500 companies, and government agencies. He’s also a New York Times bestselling author. As a writing expert and coach, Gary was inspired to create WordRake when he noticed a pattern in writing errors that he thought he could address with technology.

In 2012, Gary and his team of engineers created WordRake editing software to help writers produce clear, concise, and effective prose. It runs in Microsoft Word and Outlook, and its suggested changes appear in the familiar track-changes style. It saves time and gives confidence. Writing and editing has never been easier.