The substantive importance of punctuation in legal arguments; or, how I learned to stop worrying and love the semicolon

Most (all?) ancient languages lacked punctuation and capitalization. Egyptian heiroglyphs, Homeric Greek, Akkadian, etc. were all written in what amounts to all caps with no spaces and no way to tell (other than training and context) where one word or phrase ended and another began. In the case of heiroglyphs (and older Hebrew texts), they even lacked vowels. For many of these writers, opacity was a feature, not a bug, as it protected knowledge thought too sacred for the uninitiated.

While it's certainly possible to write now--even with our vowels, capital letters, and punctuation--to prevent easy understanding, it's not a good idea if you're a lawyer. The idea is to communicate your ideas clearly, keeping the possibility for misunderstanding to a minimum.  

Part of writing clearly is correctly--even elegantly--using punctuation for pauses. We have five commonly-used marks for this (in general ascending order of pause length): comma, semicolon, dash, colon, and period. Many times, it's just a question of style; how long do you want the reader to absorb what you've said?; do you want to connect the ideas more closely and quickly (comma, semicolon, dash) or have them digest things more slowly (colon, period)? But it can also affect the substance of legal arguments.

Use (and non-use) of the Oxford comma in a contract provides one famous example. In many ways, Marbury v. Madison was a decision about reading a semicolon in the Judiciary Act of 1789 as a period. Because the law is words, the laws governing word use and punctuation often rein supreme (absent some exception like the absurdity canon). I once had a case in which a criminal defendant was challenging his counsel's lack of objection to a jury instruction because it resembled an instruction in a prior case that had been held erroneous. I noticed that it differed from the bad instruction because its clauses were separated by semicolons rather than a colon. In my brief, I discussed the differences between the two marks and why it mattered. The court agreed with me that because the instruction had semicolons, it correctly stated the law, so counsel wasn't required to object. State v. Lopez, 438 P.3d 950 (Utah Ct. App. 2019). 

Punctuation may seem like a small thing, but it can determine the outcome of many legal issues. Use it wisely, and if you don't know the technical (as opposed to merely stylistic) differences, start learning them now. You'll be better off, and the courts will appreciate it.