Heirs of a renowned Jewish art collector won’t be able use U.S courts to sue Hungary’s government for the return of paintings seized during World War II that are worth millions.

The Supreme Court on Monday said it wouldn’t take the case. That means an appeals court ruling that Hungary is immune from being sued in U.S. courts over the paintings stands.

The family of Baron Mor Lipot Herzog is still pursuing a case in the United States against three museums and a university all run by Hungary. The family says those institutions together hold about 40 pieces that were Herzog’s but confiscated by Hungary, a wartime ally of Nazi Germany.

The family unsuccessfully tried suing in Hungary before suing in the U.S. in 2010.

(AP)