Q. Is it correct or incorrect to put a comma before the “and” in the following sentence: “The Department of Justice has taken on the role of coordinating agencies’ activities, and has undertaken several new initiatives related to dealing with criminals.” I think it’s correct because the second clause—although not an independent clause, strictly speaking—is so long (and the subject is implied). The comma seems to help the reader get through the sentence. Many thanks.
A. The comma isn’t necessary, but if you want to indicate a pause, add it anyway. Please see CMOS 6.16: “The comma, aside from its technical uses in scientific, bibliographic, and other contexts, indicates the smallest break in sentence structure. It usually denotes a slight pause. In formal prose, however, the logical considerations that are the basis of the recommendations in this chapter come first. In less formal registers and in creative works, authors will have more leeway to use commas to control the pace of their prose and to establish a certain tone. . . . Whatever choices are made should ultimately aim to serve the reader.”