Key defendant, former vice president at Airbus parent company EADS, Jean-Louis Gergorin, walks out of the Paris courthouse Monday Sept. 21, 2009 in Paris. Former French prime minister Dominique de Villepin goes on trial Monday on charges he helped perpetuate a smear campaign targeting his longtime rival, President Nicolas Sarkozy. The monthlong trial in the saga known as the Clearstream affair will also delve into old international arms deals, offshore bank accounts and the French aviation industry.