Please provide the relevant Bluebook edition and rule. (The editions I have seen require roman time for case names on the first reference, and italics for the short form of the case name in subsequent references.)
Under the ALWD, case names are always italicized, but that's a different style.
I'm sorry, you're right, fbennet. The relevant rule is 2.1(a) (18th ed.), which states, "[u]se ordinary roman type for case names in full citations," but "[u]se italics for the short form of case citations." I was relying on misinformation, my apologies.
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Under the ALWD, case names are always italicized, but that's a different style.