But the issues are very different.
The objects acquired by and returned from the Museum of Fine Arts in Boston, the J. Paul Getty Museum in Malibu, the Metropolitan Museum of Art in New York, and the Princeton University Art Museum (and not forgetting Shelby White) do not appear to have been known prior to the 1970 UNESCO Convention. Indeed many were acquired after the 1973 declaration by the Archaeological Institute of America (AIA). In other words, after 1970 (and certainly after 1973) museum curators, archaeologists and even private collectors were aware of the problems of looting and recently surfaced objects.
And some chose to continue buying and accumulating.
And the Medici Conspiracy has shown how the system worked: from the deliberate seeking out of archaeological sites (mostly tombs) to the movement of cultural property across international frontiers. There are even indications that some pots were deliberately smashed to ease the process.
Archaeologists rightly condemn such actions.
It is probably also fair to say that of the eighty or so items returned from these North American collections to Italy, not one has a recorded find-spot (a few have alleged find-spots, and some of the pieces stolen from museums had come from excavations).
In other words, the archaeological contexts have been lost for ever.
So the pressing issue for Liapis should be to take action against contemporary looting of archaeological sites within the international frontiers of the modern state of Greece.
He makes the claim:
More and more museums are adopting tighter ethics codes and governments promote bilateral and international cooperation (for the return of ancient objects).But I am not convinced that such ethical codes are working. I only have to look at the way that the 2006 Association of Art Museums Directors (AAMD) Report on the Loan of Archaeological Material and Ancient Art is ignored to realise that the debate is far from won.
Some museum directors and curators are still wanting to display freshly-surfaced antiquities. And loans are one way of getting round their professional obligations.
If Liapis looks out from the New Acropolis Museum he will be able to see the building where the Parthenon marbles were once displayed. These sculptures have not lost their archaeological context (even though many are currently residing in Bloomsbury). And they were acquired long before the 1970 UNESCO Convention - and long before somebody had even thought of the concept of the United Nations. Their return to Athens is not really about ethics - the issue is about the most appropriate place to display these sculptures from an iconic Athenian building.
Liapis needs to make two very different points and to deploy two different types of evidence.