According to L'Express, the powerful French labor union CFTC filed a complaint in 2006 against staffing firm CRIT for failure to pay 'indemnite de precarite' and 'une partie de leur conges' (unemployment compensation and earned vacation), and now the French government is prosecuting the firm.
Interesting staffing software angle: the staffing company's software firm, Agathe, has been implicated for having coded the temp workers in a way that relieved the staffing company from paying these benefits.
Although there may actually be fraud here, I highly doubt it. The staffing firm probably maintained different divisions of service (tech/labor) and had different benefit systems in place for each, which as you can imagine made it ripe for the ire of the union.
Remember in France the independent business person is guilty until proven innocent and the labor union has tremendous power. With so many laws against business on the books, independent business people are susceptible to any inspector (controlleur) that might decide to go after them.