Up through the 16th edition of the Chicago Manual of Style, the standard way to cite the same source in multiple consecutive footnotes was to use the abbreviation ibid. (16:14.29). With the 17th edition, the preferred method is now to use regular shortened citations for all subsequent citations of a work, though the title can be omitted when the same work is cited multiple times in a row (17:14.34).
The Chicago Manual’s justification for this change focuses on the reader’s experience with the final product, but from my perspective as an editor, the other problem is that ibid. makes it all too easy for citation information to get lost or jumbled in the writing and editing process. Revising one’s work involves a lot of adding, deleting, and moving sentences—if you’re not extremely careful to update the citations as you go, you’re likely to end up with ibids that have missing or ambiguous antecedents. I often encounter situations where it’s clear that an “Ibid.” footnote doesn’t refer to the previously cited source, and I can’t always determine what it’s actually supposed to be citing. If the house style for the press you’re publishing with does allow or require ibid., I’d still recommend using regular shortened citations throughout your manuscript until the final stages of revision so that you can avoid creating these problems.
Note also that according to the rule in the 16th edition, ibid. can only refer to a single source at a time, and it “must never be used if the preceding note contains more than one citation”—if one note cites three different sources and the next one just says “Ibid.,” it’s impossible to tell which source you mean (and the answer shouldn’t be “all of them”). This is another problem that can be introduced over the course of the writing process, since revision might involve adding more sources to existing notes.
Erin K. Maher, Ph.D. 