How lawyers use the word “per”, and how to avoid using it.

The word per is an example of a Latin term that has seamlessly entered everyday English, much like etc., agenda, and data. For most people, it’s just another English word.

I recently read an employment contract written in clear, plain English that used per three times:

• "Your normal hours of work are 35 hours per week."

• "We will pay you a salary of £35,000 per year."

• "Holiday leave accrues at the rate of 1/12th of the annual allowance per month."

In all these examples, per simply means “each” — each week, each year, each month. You could just as easily write “a week,” “a year,” or “a month.” There’s no definitive right or wrong choice, and anyone with a moderate understanding of English would understand per, each, or a equally well. Some lawyers prefer to avoid obvious Latinisms (e.g., using “from the beginning” instead of ab initio), but per is not usually perceived as a Latinism.

A Word of Caution

While per often implies “each,” it can also indicate a broad, approximate, or average figure. For example:

• Each suggests precision: "Work 10 hours each week" means exactly 10 hours every week.

• Per feels looser: "Work 10 hours per week" could mean 8 hours one week and 12 hours the next, as long as the average is 10 hours.

When drafting, ensure your intention is clear to avoid ambiguity.

Everyday Uses of Per

Per also sneaks into everyday language when dealing with percentages. For example:

• “This week only, 20% off all carpets!”

Here, percent comes from the Latin phrase per centum, meaning “for each hundred.” U.S. lawyers usually write it as one word (percent), while U.K. lawyers tend to use two words (per cent). Both are correct. The word percentage, however, is always written as one word. If you use the % symbol, don’t leave a gap between the number and the symbol (e.g., 20%).

When dealing with percentages, also watch the subject of the sentence:

• Singular: “Being 90% sure is enough to find the defendant guilty beyond reasonable doubt.” (90% refers to a degree of certainty, which is singular.)

• Plural: “50% of our lawyers are Harvard graduates.” (50% refers to lawyers, which is plural.)

"As Per" in Legal Writing

The phrase as per is often used by lawyers to mean “in accordance with” or “as agreed.” For example:

• “We are returning all original documents as per our client agreement letter.”

• “You are required to vacate the property as per your lease agreement.”

While it’s an informal shorthand, most readers will understand it in context.

Specialised Legal Uses of Per

• Per curiam: This refers to a judgment agreed upon by all the judges of a court, not just a majority. Instead of using per curiam, it’s clearer to write “a decision of the whole court.”

• Per Lord Denning: When quoting a judge in a case, the phrase per Lord Denning indicates that he is the source of the quoted words. However, it’s often better to write: “As stated by Lord Denning in the case of ….”

• Per incuriam: This phrase describes an error in an earlier court decision, typically when the court overlooked a binding precedent or statutory provision. It’s a polite way of acknowledging a mistake.

• Per se: In U.S. antitrust law, per se describes conduct that is inherently anticompetitive and indefensible. For example, price-fixing is a per se violation. This is conceptually similar to res ipsa loquitur in tort law, where wrongdoing is so obvious that no further proof is needed (e.g., a surgeon leaving scissors inside a patient).