BERLIN - A Berlin museum must return thousands of rare posters to an American, part of his Jewish father's unique collection that had been seized by the Nazis, Germany's top federal appeals court ruled Friday.

The Federal Court of Justice in Karlsruhe said Peter Sachs, 74, was the rightful owner of the posters owned by his father Hans, ending seven years of legal battles over a vast collection dating back to the late 19th century.

Sachs can now demand their return from the German Historical Museum, the court ruled, saying if the institution kept them that would be perpetuating the crimes of the Nazis.

The collection is now believed to be worth between C4.5 million and C16 million ($6 million and $21 million).

"I can't describe what this means to me on a personal level," Peter Sachs, who recently moved to Nevada from Sarasota, Florida, told The Associated Press in an email. "It feels like vindication for my father, a final recognition of the life he lost and never got back."

The case ended up with the Karlsruhe court because of the posters' unique and tumultuous journey through more than 70 years of German history. The posters were collected by Sachs, stolen from him by the Nazis' Gestapo, became the possession of communist East Germany for decades, and then moved to the Berlin museum after Germany's reunification in 1990.

The court acknowledged that Peter Sachs did not file for restitution of the posters by the official deadline for such claims, and that the postwar restitution regulations instituted by the Western Allies could not be specifically applied in his case. But the judges ruled that the spirit of the laws was clearly on Sachs' side.

Not to return the posters "would perpetuate Nazi injustice," the judges wrote. "This cannot be reconciled with the purpose of the Allied restitution provisions, which were to protect the rights of the victims."

Hagen Philipp Wolf, a spokesman for Germany's cultural affairs office which oversees the public German Historical Museum, said the decision would be respected.

"The Federal Court of Justice has decided, we have a clear ruling, the German Historical Museum must return the Sachs posters," he said.

A total of 4,259 posters have been identified so far as having belonged to Sachs' father. They were among a collection of 12,500 that his father owned, which include advertisements for exhibitions, cabarets, movies and consumer products, as well as political propaganda -- all rare, with only small original print runs. It is not clear what happened to the remainder.

The German Historical Museum rarely had more than a handful of the posters on display at any given time, though it had said the collection was an invaluable resource for researchers.

Sachs' attorney in Germany, Matthias Druba, said his client now hopes that he can find a new home for the collection where they can be displayed to a wider public.

"Hans Sachs wanted to show the poster art to the public, so the objective now is to find a depository for the posters in museums where they can really be seen and not hidden away," Druba told the AP.

The posters were seized from Hans Sachs' home in 1938 on the orders of Nazi Propaganda Minister Joseph Goebbels, who wanted them for a museum of his own.

Born in 1881, Hans Sachs was a dentist who began collecting posters while in high school. By 1905, he was Germany's leading private poster collector and later launched the art publication "Das Plakat (The Poster)."

After the seizure of the posters in the summer, Hans Sachs was arrested during the Nov. 9, 1938, pogrom against the Jews known as Kristallnacht and thrown in the Sachsenhausen concentration camp north of Berlin.

When he was released about two weeks later, the family fled to the United States.

After the war, Hans Sachs assumed the collection had been destroyed and accepted compensation of about 225,000 German marks (then worth about $50,000) from West Germany in 1961.

He learned five years later, however, that part of the collection had survived the war and been turned over to an East Berlin museum. He wrote the communist authorities about seeing the posters or even bringing an exhibit to the West to no avail. He died in 1974 without ever seeing them again.

The posters became part of the German Historical Museum's collection in 1990 after the 1989 fall of the Berlin Wall.

Peter Sachs has said he only learned of the existence of the collection in 2005, and began fighting then for their return.

When he receives the posters back Sachs will repay the compensation that his father received, Druba said. He said it was not yet clear what the amount would be in current terms.