Last week, … [a US] Court rejected Hungary’s motion to dismiss a claim brought against it by the heirs of Baron Mor Lipot Herzog, a well-known Jewish Hungarian art collector.

…

The Court found that (1) the defendants did not dispute that “rights in property” (2) the plaintiffs’ claim that the Herzog Collection was taken in violation of international law was substantial and non-frivolous, and therefore, adequately satisfied the second requirement; and (3) the defendants admitted that the museums and the university (both agencies or instrumentalities of Hungary) were in possession of the pieces of collection identified in the complaint which was sufficient to satisfy the ‘owned or operated’ requirement, ad these bodies were are engaged in “either a regular course of commercial conduct or a particular commercial transaction or act” in the US as of the commencement of the action.

More here: New York Times.

The judgment itself is available here (warning: pdf).

Finally, here is a comprehensive website devoted to the claim.