The Republic of Austria, the Albertina Museum, and the Leopold Museum Foundation—the latter two both in Vienna—filed a response Friday to amicus briefs submitted by two US senators, in which they repeat their claim that the updated Holocaust Expropriated Art Recovery (HEAR) Act violates Article III of the US Constitution and the Tenth Amendment.

Austria, the Albertina, and the Leopold are defendants in a suit brought by Timothy Reif, a descendant of Fritz Grünbaum, a Jewish cabaret performer and collector who was killed in a death camp in 1941. Reif is seeking the return of several works by Egon Schiele that he alleges were looted by the Nazis when they seized Grünbaum’s collection. The defendants dispute the claim, arguing that the works in question are part of the same cache that was exported from Austria by Grünbaum’s sister-in-law in the 1930s and then sold to a Swiss dealer in the 1950s.