California lawmakers have bucked one of the nation’s most powerful federal courts by enacting a new state law designed to reunite a Jewish family with an exquisite Impressionist painting that was looted by the Nazis at the dawn of World War II.

The law, which Gov. Gavin Newsom put into immediate effect with his signature Monday, was crafted in response to a U.S. 9th Circuit Court of Appeals ruling in January. That ruling found that the painting — “Rue Saint-Honoré in the Afternoon. Effect of Rain” by Camille Pissarro — was lawfully owned by a Spanish museum and need not be returned to the American descendants of Lilly Cassirer Neubauer, who surrendered the masterpiece to the Nazis for a visa to flee Germany in 1939.

The law’s passage after nearly two decades of court battles sets the stage for a renewed, last-ditch effort by the family to reclaim the masterpiece, estimated to be worth tens of millions of dollars. Assembly Bill 2867 makes clear that California law requires that Nazi looted artworks such as the Pissarro — as well as other valuables stolen during past or future acts of genocide or political persecution — be returned to their rightful owners.

“For survivors of the Holocaust and their families, the fight to take back ownership of art and other personal items stolen by the Nazis continues to traumatize those who have already gone through the unimaginable,” Newsom said in a statement. “It is both a moral and legal imperative that these valuable and sentimental pieces be returned to their rightful owners, and I am proud to strengthen California’s laws to help secure justice for families.”

Newsom signed the bill during a small gathering with the families of Holocaust survivors at the Holocaust Museum LA. Neubauer’s great-grandson David Cassirer, who lives in Colorado, attended the event and praised Newsom and the lawmakers behind the bill — including Assemblyman Jesse Gabriel (D-Encino), co-chair of the California Legislative Jewish Caucus — for “taking a definitive stand in favor of the true owners of stolen art.”

Cassirer said his late father, Claude Cassirer, who discovered the Pissarro painting had survived the war and launched the family fight for its return two decades ago, would be thrilled with his adopted state’s support.

“As a Holocaust survivor, the proudest day of my father’s life was in 1947, when he became a U.S. citizen,” Cassirer said. “He would be so happy, and grateful, that the people of the state of California have taken action to ensure the return of looted art to its rightful owners.”

Thaddeus Stauber, an attorney for the Museo Nacional Thyssen-Bornemisza, the Madrid museum that holds the Pissarro, said late Monday that he could not immediately comment.

The new law is broad in the sense that it sets out clear standards for how claims of looted artwork should be handled under California law — providing a clearer path to reclaiming such art for American families suffering political persecution in the past, present or future.

However, it is also extremely precise in its application to the Cassirer case, which it was built around and references.

Neubauer looked for the painting for years after the war with no luck and died without knowing whether it had survived the war.

Four decades later, in the early 2000s, her grandson Claude Cassirer discovered that the painting, to which she had left him the rights, had survived and was in the vast collection of the Museo Nacional Thyssen-Bornemisza, a prominent museum owned by the Kingdom of Spain.

When Claude Cassirer asked for the painting’s return, the museum refused. So he sued in U.S. federal court.

In January, a three-judge panel of the 9th Circuit ruled that the nature of the dispute required it to apply an archaic Spanish law allowing titles to stolen goods to be transferred over time — and justifying the museum’s acquisition of the painting — rather than a modern California law that comports with international agreements by calling for Nazi looted artwork to be returned to its original, rightful owners.

One of the judges on the panel, appointed entirely by President George W. Bush, said she agreed with the ruling even though it went against her “moral compass.” When a larger group of judges reviewed the decision, some found that the smaller panel had misapplied the law — but they were overruled.

With the passage of the new law, California’s lawmakers made it explicit that they think the court misinterpreted state law. The text of the new legislation specifically states that it applies to the Cassirer case and should change the outcome.

Sam Dubbin, the Cassirers’ longtime attorney, said the family will now formally challenge the 9th Circuit’s decision, including by citing the new law, which he called a “bright line” that will “prevent the ability of museums with stolen art to delay and distort, when truth and justice lie within easy reach.”

“This new law is essential for truth, history, and justice, for the Cassirer family, and future cases as well,” Dubbin said. What form the family’s legal challenge will come in, and in which court, was not yet clear.

The long court battle has substantially raised the profile — and likely the value — of the Pissarro painting itself and could set precedent useful for other families seeking the return of looted art. Attorneys, art historians and others involved in such litigation the world over have watched the Cassirer case closely.

Gabriel said his intent was for the state’s new law to protect all victims of genocide, persecution and political plundering.

“Our effort will make it crystal clear that California law must triumph over foreign law, that California stands with Holocaust survivors, and that cases must be decided based on truth, justice, and morality, not the misapplication of legal technicalities,” he said.

David Schaecter, president of the Holocaust Survivors Foundation USA, said Holocaust survivors and their families are “very grateful” to Gabriel, Newsom and other lawmakers for passing the new measure.

“Looting art and other assets from Jewish families was an essential part of Hitler’s plan to annihilate the Jewish people, and eradicate all traces of Jewish life and culture. Spain’s insistence on keeping the Cassirers’ Pissarro perpetuates the crimes of the Nazi regime, and demeans the memory of six million Jewish souls,” Schaecter said.

“The people of California should be proud that their lawmakers will not allow this to happen.”