The trial today of Thibaud Simphal and Pierre-Dimitri Gore-Coty comes a week after France's top constitutional authority upheld a 2014 law banning the low-cost UberPop service, which allowed any driver to act as a taxi.
Uber's standard app-based service remains legal in France. The two men face up to two years in prison and fines of 300,000 euros (USD 337,000).
Uber is under increasing pressure to work with skeptical European governments. It is banned entirely in Spain and Italy, but French lawmakers say they understand the demand for such services.
During protests in France this summer, taxi drivers infuriated by Uber competition smashed livery cars and set tires ablaze.