Somebody mentioned Defiant cloaking. Is there any explanation for how Starfleet still has the right to use a Romulan cloaking device when relations with the Empire have been iffy for several years?
I think that, as per their original agreement with the Romulans, they only use the cloak while they're in the Gamma Quadrant. Though, granted, it's questionable why they're allowed to keep it at all.
My suspicion has always been that it's a small loophole that Starfleet has been quietly exploiting since the end of the Dominion War. Probably permission to use the cloak has never been officially rescinded, and quite possibly given everything that happened to the Romulans after the war (Shinzon, the temporary sundering of the Empire etc) they may have even forgotten that Defiant has it.
A related question would be how does the Defiant have a cloaking device at all? Presumably the original cloaking device borrowed from the Romulans was destroyed at the Second Battle of Chin'toka along with the USS Defiant in DS9 "The Changing Face of Evil".
When the USS Sao Paulo replaced, and then became, the USS Defiant in DS9 "The Dogs of War" I don't think there was any mention of a cloaking device being aboard her. And I don't remember her using a cloak in that episode, nor in the next one, "What You Leave Behind", which was, of course, the last episode of the series. Plus, I don't remember any discussion about this in the DS9 relaunch novels, but I may be forgetting something.
Much like the incorrect registry number (she should have the Sao Paulo's number not the same as the old Defiant), I think many writers have forgotten this fact, merging the USS Sao Paulo too completely into the USS Defiant.
So if the USS Defiant of 2383 does have cloaking technology (which it clearly does in Raise the Dawn
) then I don't think it's ever been explained where she got it from. I would think it was most likely from a source other than the Romulans, since they surely would have asked for it back by now. Hey, maybe it's a Suliban cloak.