WARSAW -- In a country where close to 3.2 million Jews are estimated to have died during more than five years of Nazi rule, the events of World War Two remain politically charged.
A significant body of research suggests that, while thousands of Poles risked their lives to help Jews, thousands also participated in the Holocaust.
But Poland's governing nationalist Law and Justice party (PiS) has said it views any investigation into complicity by Poles in the wartime slaughter of Jews as dishonoring the country.
One book on that topic, "Night without an end. Fate of Jews in selected counties of occupied Poland," names Edward Malinowski as one such collaborator.
His 81-year-old niece, Filomena Leszczynska, is suing the book's editors, Barbara Engelking and Jan Grabowski, for tarnishing his memory with a claim that her lawyer says they have not proved.
In 2018, an international backlash forced PiS to drop a law that would have made it a crime to suggest Poland bore any responsibility for Nazi atrocities.
For Grabowski, Tuesday's case covers similar ground by attempting to establish offense to national dignity as grounds for suing over any future similar claims.
"If these terms, national pride, national dignity, find their way into Polish civil litigation and procedure, that will be the end of us writing history... of the Holocaust in Poland in the way we do," he told Reuters.
Other Polish academics as well as Jewish organizations such as Israel's Yad Vashem have also expressed concern that the trial may undermine freedom of research.
The case is being funded by the Polish League Against Defamation, which opposes claims of Polish involvement in the murder of Jews.
Leszczynska's lawyer, Monika Brzozowska-Pasieka, denies it aims to introduce new avenues for litigation.
"We say that the authors violated the personal rights of Filomena by identifying her uncle as an accomplice, as a murderer, simply," she said.
Brzozowska-Pasieka argues that the historians failed to follow correct research methodology when compiling the book, an accusation that Grabowski denies.
Polish Jews account for around half the Jews estimated to have been killed in the Holocaust. A further 3 million non-Jewish citizens also died under Poland's Nazi occupation.
"There are (Polish) people who did good things (then). There are people who did bad things," said Poland's Chief Rabbi Michael Schudrich.
"If you cannot face the bad things that you have done in the past it limits the chances of you ever becoming better in the future."
Reporting by Alan Charlish, Anna Wlodarczak-Semczuk and Kacper Pempel, additional reporting by Joanna Plucinska; editing by John Stonestreet
