PARIS — More than a year after resigning in disgrace as the managing director of the International Monetary Fund, Dominique Strauss-Kahn is seeking redemption with a new consulting company, the lecture circuit and a uniquely French legal defense to settle a criminal inquiry that exposed his hidden life as a libertine.

Mr. Strauss-Kahn, 63, a silver-haired economist, is seeking to throw out criminal charges in an inquiry into ties to a prostitution ring in northern France with the legal argument that the authorities are unfairly trying to “criminalize lust.”

That defense and the investigation, which is facing a critical judicial hearing in late November, have offered a keyhole view into a clandestine practice in certain powerful circles of French society: secret soirees with lawyers, judges, police officials, journalists and musicians that start with a fine meal and end with naked guests and public sex with multiple partners.

In France, “Libertinage” has a long history in the culture, dating from a 16th-century religious sect of libertines. But the most perplexing question in the Strauss-Kahn affair is how a career politician with ambition to lead one of Europe’s most powerful nations was blinded to the possibility that his zest for sex parties could present a liability, or risk blackmail.