CNN reported that Clarke plagiarized portions of his 2013 masters thesis on US security, but the charge itself is rather wonky.
Clarke lifts language from sources and credits them with a footnote, but does not indicate with quotation marks that he is taking the words verbatim.So in answer to the question, I'll keep this in mind, but failure to use quotation marks isn't likely to make me rush to the drawing board. There are plenty of worse things in Clarke's record.
According to guidelines on plagiarism posted on the Naval Postgraduate School's website, "If a passage is quoted verbatim, it must be set off with quotation marks (or, if it is a longer passage, presented as indented text), and followed by a properly formulated citation. The length of the phrase does not matter. If someone else's words are sufficiently significant to be worth quoting, then accurate quotation followed by a correct citation is essential, even if only a few words are involved."