Strauss-Kahn, 65, who settled a US civil case with chambermaid Nafissatou Diallo after criminal charges were dropped, risks as much as 10 years in jail and a fine of up to €1.5m if convicted in the French trial.
Investigating magistrates who sent Strauss-Kahn to trial with 13 others argue he knew he was dealing with prostitutes when taking part in sex parties in Paris, Lille, and Washington from 2008 to 2011, a judicial source said.
He is charged with “pimping with aggravating circumstances”.
Defence lawyers for Strauss-Kahn have flatly dismissed those allegations, arguing he never made a secret of his penchant for swinger parties but was unaware the women present were prostitutes and did not play any pivotal organisational role.
Defence lawyer Richard Malka said he had nothing to add ahead of the opening of the trial in the northern city of Lille. The affair has come to be known as the Carlton Affair, named after the Lille hotel at the centre of a sex ring.
Strauss-Kahn, who starred as finance minister in a boom-time Socialist government in the late 1990s, became one of the world’s most influential decision-makers in 2007 as head of the International Monetary Fund.
That high-flying career ended in May 2011 when the world witnessed live TV images of the then IMF chief being escorted handcuffed into custody in New York.