Citation, Documentation of Sources

Q. Our group has chosen The Chicago Manual of Style as a reference for our university translation project (textbook on international trade). What I’d like to know is whether, since we have chosen CMoS, it now supersedes the capitalization rules used by the publishing agencies of works cited in the text. For example, would it be “Customs—Trade Partnership Against Terrorism” as it appears on their website or “Customs—Trade Partnership against Terrorism,” following CMoS rules for lowercasing prepositions?

A. The latter. Choosing a style guide means that you will edit your documents to conform to that guide. It’s actually one of the primary purposes of having a guide. Titles in original published works feature various display styles—all caps, small caps, italics. There’s really no way a writer or editor can be expected to research and reproduce the exact appearance of the title page of every book. Since you’ve decided to follow CMOS (yay!), you will lowercase “against” per CMOS 8.159.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]