More coverage of the acquisition guidelines  for US museums, brought in largely to try & avoid repeats of some of the court cases that have occurred in recent years. These are however still only guidelines, so museums are free to ignore them & they don’t apply retroactively.
New Guidelines for Collecting Antiquities
Published: June 4, 2008
NEW YORK—After a year and a half of discussions, the Association of Art Museum Directors has announced new guidelines for collecting antiquities, reports the New York Times. The new policy uses 1970, the year UNESCO ratified a landmark convention prohibiting trade in illegal antiquities, as its starting point, saying a museum “normally should not” acquire a work unless it has solid proof that the object was outside of its country of probable modern discovery before 1970, or that the object was legally exported from its country of probable modern discovery after 1970.
The association commented that although the new policy will make building antiquities collections through typical means such as purchases and gifts from wealthy donors more difficult, it will hopefully help the archaeological field curb the current trade in illegally dug-up objects. The previous policy had set a 10-year rolling cutoff.
Plans are also in the works for the creation of an Internet database where members can find information about newly acquired artifacts, making the museum collecting process much more transparent.
Ultimately, the decision to acquire an object remains with the given museum, a policy about which some archaeologists and experts have expressed concern. “On an overarching level this is a significant step forward,” said Patty Gerstenblith, the president of the Lawyers’ Committee for Cultural Heritage Preservation. But, she commented, “the fact that a museum can use its own informed judgment obviously leaves a lot of discretion, a lot of room for exceptions.” Many experts had hoped to see the 1970 cutoff set as a rule, rather than a guideline, as it already is at the British Museum, the J. Paul Getty Museum, and a number of other large institutions.