A Berlin museum must return thousands of rare posters to an American man, 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 confirmed Peter Sachs, 74, was the rightful owner of the posters collected by his father Hans and ruled he is entitled to receive them back from the German Historical Museum.

The ruling ended seven years of legal battles over a vast collection dating back to the late 19th century that is now believed to be worth between euro4.5 million and euro16 million ($6 million and $21 million).

The court said if the museum kept the posters it would be akin to perpetuating the crimes of the Nazis.

"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.