"What are the museums to do, they ask, if the artist retained the copyright, if the artist cannot be found, or if a group of heirs is arguing about who owns which copyright?"
That's a quote from today's Supreme Court decision in the Kirtsaeng case, holding that the first-sale doctrine applies to works made abroad. Which (among other things) means museums can continue to display foreign-made works in their collections. Adam Liptak's New York Times story is here. Sergio Muñoz Sarmiento comments here. Yale's Margot Kaminski has a good post here.