Q. If words in parentheses would turn a singular subject into a plural subject, should the verb (outside the parentheses) be plural? I’m wondering specifically whether “applies” should be “apply” in this sentence: A case such as this illustrates a broader category in which justice (and, therefore, injustice) no longer applies.
A. Your sentence is correct as written. Parenthetical content should not leach into the syntax of the containing sentence. If the information is so important that you feel it shouldn’t be ignored, take it out of parentheses: A case such as this illustrates a broader category in which justice and injustice no longer apply.