Two Museums Fight New Laws in Nazi-Looted Art Cases
Two museums that have already won a Nazi-looted art case are now fighting the laws that could decide it again. The Thyssen-Bornemisza Collection Foundation in Madrid and the Norton Simon Museum in Pasadena, California, are challenging new California and U.S. federal rules for claims over art seized by the Nazis, The Art Newspaper reported on 28 October 2026.
The painting at the centre of the fight is Camille Pissarro's Rue Saint-Honoré, après-midi, effet de pluie, from 1897. Baron Hans-Heinrich Thyssen-Bornemisza bought it from a New York dealer in 1976, without knowing it was Nazi loot. In 2020, a U.S. appeals court ruled that the foundation could keep it.
The case did not stay closed. David Cassirer and other heirs of Lilly Neubauer say she was a Jewish woman living in Berlin when, in 1939, she was forced to sell the painting to Nazis to get an exit visa. They say she was never allowed to collect the payment.
Courts had earlier applied Spanish property law. A 2022 federal appeals decision said the foundation owned the painting under acquisitive prescription, a rule under which long possession can turn into legal ownership. Prior proceedings found the foundation had held the work for more than three years without knowing it was stolen.
Then California changed its rules. In 2024 the state amended its procedural laws to make it easier for residents to sue museums over stolen art. The U.S. Supreme Court ordered the Pissarro claim reconsidered in 2025, and vacated the earlier decision. Under the new state statute, California substantive law applies to these claims, whatever earlier judges decided.
Heirs now argue that California property law applies, and that under it good title can never be acquired to stolen property. The foundation argues the state law is unconstitutional. It says the law retroactively takes away its vested property rights in the painting without due process.
Federal law is part of the picture too. An amendment to the Holocaust Expropriated Art Recovery (HEAR) Act, passed by Congress, took effect in April 2026 and expressly covers pending lawsuits. For covered Nazi-loot claims, it stops possessors from relying on time-based defences, including acquisitive prescription.
Both the museum and the plaintiffs have asked for summary judgment, a ruling made on written filings rather than a full trial. Judge John Walter of the federal district court in Los Angeles said he will decide the Thyssen-Bornemisza case on the submitted briefs, without oral argument. No decision has been issued yet.
The fight is not confined to these two museums. In the week of 16 September 2026, two new lawsuits were filed in California demanding that museums return Nazi-looted art, the Los Angeles Times reported. One of them concerns a Renaissance painting that the plaintiffs say the Nazis looted, according to Courthouse News.
For the families involved, the questions are simple even if the law is not. Who held the painting, when did they know its history, and which country's rules decide? Those answers will settle who keeps the work and who gets paid.
