New Revelations Reignite a 17-Year Battle Over the Guelph Treasure: A Pivotal Shift in the Restitution of Nazi-Looted Art

New Revelations Reignite a 17-Year Battle Over the Guelph Treasure: A Pivotal Shift in the Restitution of Nazi-Looted Art

By: Fern Sidman

A significant development has cast new light on one of the most contentious restitution cases in modern European history — the battle over the Guelph Treasure, a glittering trove of medieval religious artifacts valued at approximately $300 million. As The New York Times reported on Wednesday, recently unearthed documents in a German archive have reinvigorated this long-running legal and moral struggle, suggesting that the 1935 sale of the treasure was made under duress during the Nazi era.

The trove, renowned for its exquisite craftsmanship and profound historical significance, consists primarily of gem-studded ecclesiastical relics, including ornate reliquaries and crosses. Among these treasures, the most prized is a 12th-century reliquary shaped like a Gothic church, made from gold, silver, and copper, and adorned with walrus tusk-carved biblical figurines — a stunning embodiment of medieval artistry.

According to the information provided in The New York Times report, the origin of the legal dispute dates back to 2008, when the heirs of four Jewish art dealers — Isaak Rosenbaum, Saemy Rosenberg, Julius Falk Goldschmidt, and Zacharias Max Hackenbroch — launched a restitution claim against the current custodian of the Guelph Treasure, the Prussian Cultural Heritage Foundation in Berlin. The dealers were part of a consortium that had previously owned the treasure before its sale in 1935, a period marked by increasing Nazi persecution of Jews. Despite substantial research, the exact composition of this consortium has remained elusive, complicating the legal case over the years.

Now, a new chapter has emerged in this decades-old saga. The New York Times report indicated that the heir of another consortium member, Alice Koch — whose ownership stake had previously been overlooked — has come forward with a separate claim. Legal representatives for Koch’s heirs have presented newly discovered archival evidence indicating that Koch sold her share of the Guelph Treasure under duress and was subsequently forced to pay the punitive “Reich Flight Tax” in October 1935 before fleeing to Switzerland.

The documents, uncovered by Berlin-based attorney Jörg Rosbach, reveal that Koch was compelled to use the proceeds from the treasure’s sale — finalized just four months prior — to pay the exorbitant tax, which amounted to 1.2 million Reichsmarks, a sum equivalent to millions of dollars today. Rosbach emphasized to The New York Times that this discriminatory levy, imposed exclusively on Jews seeking to emigrate from Germany, renders the sale involuntary by any reasonable legal and moral standard. “One of the important questions in determining whether a sale was under duress is whether the seller was able to dispose of the revenue freely,” Rosbach said. “Alice Koch was not.”

This newly surfaced evidence has prompted the Prussian Cultural Heritage Foundation to agree to a new hearing with the German government’s advisory commission on Nazi-looted art. As The New York Times report pointed out, this is a noteworthy shift given that the commission had previously rejected the claims made by the other four heirs in 2014. At the time, the commission acknowledged the persecution of the Jewish dealers but stated that there was no evidence to suggest coercion in the negotiation process.

The heirs of the original four dealers pursued their claim further in the United States, initiating a legal case that escalated to the Supreme Court. However, in July 2023, their pursuit came to an end when the Court of Appeals for the District of Columbia upheld a prior ruling that U.S. courts did not have jurisdiction over the matter, effectively closing the American legal pathway.

Yet, just as one avenue has closed, another appears to be opening. As The New York Times also reported, Germany is now preparing a fundamental shift in how it handles restitution claims for art looted under Nazi rule. The government has announced plans to dismantle its current advisory commission — a non-binding body whose recommendations carry moral but not legal force — and replace it with a binding arbitration tribunal. Although the timeline for this transition remains uncertain, the move could mark a turning point for unresolved cases like that of the Guelph Treasure.

The Guelph Treasure was purchased in 1929 by a consortium of Jewish art dealers with the intent to sell it for profit. The dealers successfully sold about 40 items, largely in the United States. But in 1935, during the tightening grip of Nazi rule, the remaining 44 pieces were sold to the State of Prussia — a government entity then under the control of Hermann Göring, Adolf Hitler’s closest political enforcer, according to The New York Times report.  It is this 1935 sale, made under increasingly oppressive conditions for Jews in Germany, that lies at the center of a complex legal and ethical storm.

Aa dramatic shift in the case occurred in 2022 when Berlin attorney Jörg Rosbach presented new archival evidence to the Prussian Cultural Heritage Foundation, the institution currently in possession of the Guelph Treasure, The New York Times report explained. Rosbach represents the heir of Alice Koch, a previously unrecognized member of the original consortium who owned 25 percent of the collection.

The documents reveal that Koch sold her share of the treasure in 1935, only to be forced to pay the punitive and antisemitic “Reich Flight Tax” later that year before fleeing Germany for Switzerland. Koch was compelled to use the proceeds from the sale — estimated at 1.2 million Reichsmarks (millions in today’s dollars) — to satisfy this Nazi-imposed tax, effectively stripping her of any real benefit from the sale.

“This was a discriminatory tax used against Jews,” Rosbach told The New York Times. “One of the important questions in determining whether a sale was under duress is whether the seller was able to dispose of the revenue freely. Alice Koch was not.”

Despite Rosbach’s overtures in 2022, negotiations with the Prussian Cultural Heritage Foundation remained stalled by April 2023, prompting him to formally file a claim with Germany’s advisory commission on Nazi-looted art. Simultaneously, Markus Stötzel, representing the heirs of the original four Jewish dealers — Rosenbaum, Rosenberg, Goldschmidt, and Hackenbroch — also filed a new claim.

The commission’s procedural rules, however, require consent from both the claimant and the holding institution before a case can be heard — a long-standing source of frustration for restitution advocates. As The New York Times report noted, heirs accused the foundation of “delaying tactics,” prompting the German culture minister and the advisory commission itself to pressure the institution into consenting to a new hearing.

Hermann Parzinger, president of the Prussian Cultural Heritage Foundation, acknowledged to The New York Times that the newly uncovered evidence represents “a new aspect that we have to take very seriously.” He defended the delay in part by citing the need to identify all possible claimants, noting that “despite comprehensive research… the original composition of the consortium that sold the Guelph Treasure in 1935 is not fully known.”

The Guelph Treasure case may be among the final controversies adjudicated by Germany’s existing advisory commission. As The New York Times report highlighted, the German federal government and the country’s 16 states have announced plans to disband the commission and replace it with a binding arbitration tribunal.

Unlike the current commission, the new tribunal would allow claimants to file disputes unilaterally — a transformative shift aimed at breaking the longstanding gridlock that has enabled museum trustees to block proceedings simply by withholding consent.

This long-overdue reform, as many see it, is set to be implemented under the incoming government led by Friedrich Merz of the Christian Democratic Union. Coalition negotiations with the Social Democratic Party are still ongoing, and a new culture minister has yet to be named. Nevertheless, legal scholars cited by The New York Times, such as law professor Benjamin Lahusen of the Europa-Universität Viadrina, believe the plan has passed the “point of no return.”

Still, until the new tribunal is operational, the advisory commission remains the only recourse for claimants — leaving cases like the Guelph Treasure mired in procedural uncertainties.

Further complicating the landscape, The New York Times reported that a third group of claimants has entered the fray: heirs of jeweler Hermann Netter — another original 25 percent owner of the Guelph Treasure — along with another heir from the Koch lineage. Represented by yet another law firm, these heirs have begun discussions with the Prussian Cultural Heritage Foundation but have not yet submitted a formal claim.

The simultaneous emergence of multiple heirs, legal representatives, and procedural frameworks speaks volumes about the growing complexity of a case already steeped in historical ambiguity and legal opacity.

Whether this treasure — rich in cultural meaning and shadowed by tragic history — will ever be returned to the rightful heirs remains uncertain. But what is increasingly clear is that the Guelph Treasure is no longer just a collection of medieval artifacts. It is a legal and moral crucible — one that will shape the future of how nations reckon with the crimes of their past.