The case may cast new light on the events of nearly 60 years ago, when the German occupiers of France, voracious for works of art, pillaged the collections of the country's wealthiest Jewish families.
A book, first published in France in 1995, accused the late Georges Wildenstein of doing business with Nazi dealers during the war, at first in France and later, through a third party, from New York. The book does not allege that the late Mr Wildenstein was dealing in art taken from other Jewish families; only that he dealt with the Nazis while such thefts - and the systematic arrests and murders of Jews - were going on in Europe.
Mr Wildenstein's son, Daniel, and his grandsons Guy and Alec - who was in the news recently because of a colourful divorce case - are suing the author for $1m (pounds 630,000).
They accuse him of besmirching the family name and damaging the family art business, Wildenstein and Company, based at East 64th Street in Manhattan.
The defendant is Hector Feliciano, an American investigative writer regarded as one of the world's leading experts on looted Nazi art.
His book, The Hidden Museum, was responsible for shaming the French authorities into reopening the cases of thousands of art works, which had been stolen by the Nazis but never returned to their owners or their descendants. Many of the stolen works eventually passed into the French national collection. Mr Feliciano, who is counter-suing the Wildensteins, accusing them of trying to discredit him, says that the disputed information comes mostly from British and American intelligence reports.
Wildenstein and Co is one of the most powerful, and secretive, players in the international art market. The company is said to have hundreds of works of art in storage - including long-unseen Picassos and scores of unknown Fragonards - which it may, or may not, place on the market when the time is right.
Mr Feliciano's book has led to an entirely separate legal action in America, in which another Jewish family is claiming the ownership of eight medieval manuscripts held by the Wildenstein Gallery. The manuscripts, seized by the Nazis, were claimed by the Wildensteins after the war, but the other family, alerted by information in Mr Feliciano's book, insists that they belong to it.
This claim seems to have helped to persuade the publicity-shy Wildensteins to take action to clear their name. The family has been wounded recently by lurid publicity over Alec Wildenstein's divorce, during which he alleged that his wife, Jocelyne, 52, had become addicted to plastic surgery. Her strange appearance led to her being called "The Bride of Wildenstein" in the press.
The Hidden Museum deals only briefly with the late Mr Wildenstein, who died in 1963, but makes four specific claims about his actions. First, that he dealt with Nazi art brokers before 1939. Second, that he met a Nazi art dealer in France after the German occupation but before he left for New York in January 1941. Third, that he placed the family art firm in Paris in the hands of a non-Jewish employee and sent him detailed letters, through non-occupied France, directing his dealings with Nazi collectors and brokers. Fourth, that this employee, Roger Dequoy, remained with the firm after the Second World War.
The Wildenstein family says the intelligence reports on which the claims are based are false; that Mr Dequoy's war-time dealings were purely his own affair; and that the book fails to mention Georges Wildenstein's Resistance activities, for which he was honoured after the war.
In a telephone interview yesterday, Mr Feliciano said he was "surprised" that the Wildensteins brought the action since the existence of the intelligence reports were well known.
He also said that the family took no action when the book was first published in France, but only when the magazine Vanity Fair and ABC Television cited large extracts of the American version of the book in 1997. "But they are suing me in France, not in the US," said Mr Feliciano, "because freedom of speech is more systematically protected in the US, while in France, the courts seem to deal with such things case by case."
After a brief hearing today, the three judges are expected to study written pleadings, and to give a ruling next month.Reuse content