Are you referring to some particular legal entity here, or just an overall concept?
In other cases, Spain has won the rights over salvaged treasure from sunken Spanish ships, as the countries they plundered the gold from weren't countries at the time, but colonies of Spain (for example: Peru).
Sincerely, if this is in International waters, you would think there was a expiry date of shipwrecks and it's finders-keepers after, Oh, I dunno, a few hundred years or so.
However, I realise there's not much demand for such a move, so it's not going to happen any time soon, if at all.
And I would like to think that most of the Spaniards agree with that.
Also, all the global empires have been built on the same coercive foundation, and that doesn't make them "regimes".
http://historynewsnetwork.org/article/7302
Well, it looks like there was, in fact, a vast genocide. In the north and also the south americas. Really sad...
http://www.tulanemaritimejournal.org/finders-weepers-losers-...