Six Rules You Should Master—And I Can Prove It!

When it comes to correct English, “the lunatics are running the asylum,” says Steven Pinker in his new book, A Sense of Style.

In a long chapter titled “Telling Right from Wrong,” Pinker tries to clear things up, offering advice on everything from ending sentences with prepositions (it’s okay, he says, if the result would deliver “a crucial bit of information”) to distinguishing between who and whom (“writers should calibrate their use of ‘whom’ to the complexity of the construction and the degree of formality they desire,” he says).

The jury is still out when it comes to whether all this calibrating is better than just learning rules and sticking to them, at least when you’re writing for work. But which “rules” are really rules, and which ones are really worth knowing?

I’m going to try to transform those two subjective questions into one objective one: Which rules do the best legal writers invoke and apply with confidence? I can give you an empirical answer, because I’ve developed various standardized writing assessments over the years and have linked the results with real-world performance.

Although I need to keep most of these statistics close to the vest, below I will share six usage issues that, on my assessment, are highly correlated with broader measures of writing ability. Those rules count among the rules I would master. I will also share six more issues that still correlate with broader measures, but much less so, and that thus probably don’t matter that much.

I thought you might also want to know how difficult different rules are for smart attorneys, and not just how important they appear to be. So below you’ll find two tables with three columns each:

  1. The rule as it is triggered on the assessment
  2. How hard that rule appears to be for a large sample of BigLaw associates
  3. The point-biserial correlation between that rule and broader measures of writing skill

Six Rules with a High Correlation: Learn These!

Rule tested Difficulty for BigLaw associates Point-biserial correlation
Distinguishing between which and that for nonrestrictive vs. restrictive phrases Difficult .52
Spotting and fixing faulty parallels in complex either . . . or constructions Difficult .52
Spotting and fixing dangling participles Moderate to difficult .47
Using objective case of pronoun in predicate Moderate .43
Using subjunctive mood for counterfactual conditions Moderate .42
Punctuating a midsentence “however” Moderate .42
Avoiding “fused participle” and knowing when to use a possessive gerund Very difficult .42

Six Rules with a Low Correlation: Don’t Worry, Be Happy!

Rule tested Difficulty for BigLaw associates Point-biserial correlation
Distinguishing between “who,” on the one hand, and “that” or “which,” on the other Moderately easy .23
Distinguishing between “compare with” and “compare to” Difficult .20
Preferring “center on” to “center around” Moderate .16
Avoiding commas after coordinating conjunctions at the start of a sentence Moderate .15
Distinguishing between “as” and “like” in comparisons Moderately easy to moderately difficult .15
Using past perfect appropriately when multiple events in the same sentence took place in the past Moderate .11


  • Andrea

    Ross – I’m still enjoying your tips and tricks. I took your class 6 years ago and am known in my office for concise written communications. Thanks!

    • Ross Guberman

      Alfredo, thanks so much and best wishes, and Andrea, great to hear from you and congrats! Still at GW believe it or not, though only in the spring.

  • Ross Guberman

    Great to hear! Thanks so much for staying in touch.

  • Alfredo

    I am a paralegal who is learning a lot from you book. Great job Ross!!

  • Brian

    Doesn’t the list of six rules with a high correlation have seven entries?

  • Ross Guberman

    Brian, yes, because of the tie with the three-way .42 correlation! I should probably change to “seven” rules, though.