One of the lessons from the so-called Medici Conspiracy --- but also the Schinousa and the Becchina archives --- is that recently surfaced archaeological material has passed through well-known dealers and auction houses in Europe (including London) and North America. It is also clear that these same objects were acquired by major public museums as well as by a number of private collectors.
Yet at the time of acquisition there does not seem to have been documented and authenticated evidence that the objects had been circulating in the period before the 1970 UNESCO Convention. Oral histories and incomplete paperwork seem to have been acceptable (and can now be shown in some cases to have been falsified).
The fact that this same material continues to surface on the market at very regular intervals suggests that some auction houses and dealers do not appear to be taking the matter seriously. They should as the resulting negative publicity can unsettle potential buyers. After all, who would want to spend serious money on an object that may have to be returned (without compensation) to (say) Italy.
There are continuing concerns about the potential for material derived from some of Rome's eastern provinces to be surfacing on the market at the present time. To what extent have the due diligence processes been tightened? What safeguards have been put in place to ensure that the paperwork was been checked?
The due diligence process for antiquities needs to be sufficiently rigorous to prevent so-called illicit material from entering the market.