Q. Are “ius gentium” and “jus gentium” equally correct, assuming I’m consistent throughout my essay? I’m used to using “jus,” but many of the sources I’m consulting use “ius”; if I quote a passage with this word, may I simply anglicize it to “jus” without comment?
A. The spellings “ius gentium” and “jus gentium” are equally correct, though we, too, would prefer the anglicized form (to follow Merriam-Webster, not to mention the OED and other standard English-language dictionaries). But do not change “ius” to “jus” in direct quotations; readers wishing to follow your work might be confused by such a change (or, worse, prevented from finding the term). At most, provide a parenthetical gloss at first mention:
jus gentium (or ius gentium)
If the first mention is within a quotation, use square brackets:
ius gentium [jus gentium]