LawProse Lesson #198: Commas with coordinating conjunctions.

Commas with coordinating conjunctions. Many writers struggle with whether to use a comma in a compound sentence whose clauses are joined by a coordinating conjunction (and, but, or, nor, for, yet, so). Although some examples may be tricky or complicated, most of the time some basic rules apply. Here’s a refresher on the fundamentals: 1. Use a comma when you’re joining two independent clauses (that is, two subject–verb constructions that can stand alone as complete sentences) with a coordinating conjunction. Ex.: Matthew’s biological mother sued for custody, and his biological father (oddly enough) sued for support. [and used to join two complete sentences] Ex.: Every math teacher at Ellis Middle School supports the use of calculators in the classroom, yet the principal won’t allow the students to use them. [same with yet] 2. Avoid using a comma before the second part of a compound predicate—a single subject plus two verb phrases. Use a comma only if omitting it creates an ambiguity or miscue. Ex.: At his initial interrogation, the defendant refused to answer the officers’ questions and demanded to speak with his lawyer. [defendant is the subject of both refused and demanded] Ex.: Susan saw the figure who lurked in the corner, and shrieked in surprise. [Susan is the subject of both saw and shrieked. The comma prevents a misreading: without the comma it sounds as though the figure shrieked.] 3. A comma is not necessary if the clauses are short and closely linked. Ex.: Kendra went inside and I walked out. Ex.: The band played loudly yet nobody could hear. 4. If either of the clauses is complex or contains an internal comma, a semicolon generally is the better choice. Ex.: The owners agreed to pay overtime, improve safety measures, and provide additional sick days; and the strike finally ended. 5. Avoid using a comma after a coordinating conjunction that begins a sentence. Ex.: But if the defendant had told his manager about the inventory shortage, the matter would not have ended up in court. Ex.: And so the court granted the defendant’s motion for summary judgment. Even if you memorize these guidelines, the comma can cause trouble. There’s also a subjective element involved—the writer’s style. Keep in mind the comma’s role as a guidepost to help readers get through your sentences smoothly and without miscues. Further reading: The Redbook: A Manual on Legal Style § 1.4, at 4–5, §§ 10.47–10.48, at 212–13 (3d ed. 2013). Garner’s Modern American Usage 676 (3d ed. 2009). The Chicago Manual of Style § 6.28, at 316–17, § 6.57, at 326 (16th ed. 2010).