Stricter guidelines have been announced by the Association of Art Museum Directors in the USA. These revised guidelines will not of course apply retrospectively to the huge numbers of acquisitions with which many institutions are filled that took place before these guidelines were implemented.
New Yorks Times 
Museums Set Stricter Guidelines for Acquiring Antiquities
By RANDY KENNEDY
Published: June 4, 2008
After a year and half of deliberations, the directors of the country’s largest art museums will announce new guidelines on Wednesday for how their institutions should collect antiquities, a volatile issue that has led in recent years to international cultural skirmishes and several highly publicized art restitution cases.
The Association of Art Museum Directors, whose 190 members also include leaders of Canadian and Mexican museums, says the new policy will probably make it even more difficult for museums to build antiquities collections through purchases or, as is more often the case, through gifts and bequests from wealthy private collectors. But they assert that the change will help stanch the flow of objects illegally dug up from archaeological sites or other places.
The new policy advises museums that they “normally should not” acquire a work unless solid proof exists that the object was outside its country of probable modern discovery before 1970, or was legally exported from its probable country of modern discovery after 1970. That is the year Unesco ratified a landmark convention prohibiting traffic in illicit antiquities, and it has become a widely accepted cutoff for antiquities collecting.
Objects that appear on the market without documentation leading back that far are much more likely to have been stolen or illegally dug up and smuggled out of their countries. Many in the archaeological field argue that museums and private collectors create an incentive for looting by accepting artifacts whose provenance is uncertain.
A previous guideline had established a rolling 10-year cutoff. But while the new museum policy now accepts 1970, it leaves the ultimate decision on whether to buy or accept such objects up to individual museums.
“The museum must carefully balance the possible financial and reputational harm of taking such a step against the benefit of collecting, presenting and preserving the work in trust for the educational benefit of present and future generations,” the guidelines say.
The association will also create a new centralized Internet database through which its members can provide detailed information about newly acquired antiquities, part of an effort to make that area of museum collecting much more transparent.
“We’re not, in a nutshell, adopting 1970 as a hard and fast bright line,” said Dan L. Monroe, director of the Peabody Essex Museum in Salem, Mass., and the chairman of the committee that formulated the new policy. “We simply don’t see the world in such black and white terms. The facts on the ground are that such acquisitions have been extremely complex, and they need to be dealt with on a case-by-case basis.”
The immediate reaction to the new policy among archaeologists and others who have lobbied for stringent collecting standards was generally favorable. But some said they had hoped the policy would make the 1970 cutoff inviolable, as many university museums and some large museums — including the British Museum, the J. Paul Getty in Los Angeles and the Indianapolis Museum of Art — have done.
“On an overarching level this is a significant step forward,” said Patty Gerstenblith, a law professor at DePaul University in Chicago and the president of the Lawyers’ Committee for Cultural Heritage Preservation.
Still, she added, “the fact that a museum can use its own informed judgment obviously leaves a lot of discretion, a lot of room for exceptions.”
Ms. Gerstenblith also criticized the spirit of the guidelines, which speak primarily of the museums’ need to balance acquisitions against potential harm to their reputations or to their finances should they have to return a valuable object that is later found to have been looted.
“It does not seem to take into account the possible damage to the world’s cultural heritage and to archaeological sites in source countries,” she said.
But Michael Conforti, the new president of the directors’ association, said the new policy — which is not legally binding on the member museums, though he predicted that all of them would abide by it — would send a powerful signal to the antiquities market.
“If there are those out there who see this as just some kind of veiled license to collect, then they’re going to have to explain that to me,” he said. “I think this is a more than honorable stance, and one that will actually help the archaeological field.”