The Holocaust Memorial is seen at the California Palace of the Legion of Honor in San Francisco, California on Sunday. Photo: AFP

A Polish appeals court on Monday overturned a ruling against two leading Holocaust historians accused of defamation, in a case that raised questions about the freedom to research Poland's World War II past.

The civil case was brought against the academics for a book they co-edited about the complicity of Catholic Poles in the genocide of Jews during the wartime Nazi German occupation.

"Night Without End" documented several such cases, but the court action was brought by the niece of Edward Malinowski, the wartime mayor of the village of Malinowo in Poland. 

The book mentions that he may have been implicated in a local massacre of Jews by German soldiers, but the plaintiff argued the mayor had in fact helped Jews.

In February, a lower court ordered researchers Barbara Engelking and Jan Grabowski to apologize to the plaintiff, saying their claim had been "inaccurate."

On Monday, Judge Joanna Wisniewska-Sadomska overturned that ruling, though she did not speak to the accuracy of the book's passage. 

Instead, she said that the litigation constituted "an unacceptable violation of the freedom of scientific research and the freedom of expression."

Verifying research methodology or source material would make for "an unacceptable form of censorship and interference in the freedom of research and scientific work," she added.

A Warsaw-based organization that supported the niece said it would appeal to the Supreme Court. 

AFP