The ex-president Nicolas Sarkozy has personally appeared in the court.
He is accused of corruption and an attempt to bribe a judge, BBC reported.
These hearings are not the only headache for 65-year-old Sarkozy - a lively conservative who remains extremely popular with a large part of the French population. He will have to fight off claims in other courts about the financial impropriety of his election campaigns.
Sarkozy calls the persecution a witch hunt. He is sure that the liberal judiciary declared him a vendetta for reproaches of being too lenient towards criminals and attempts to limit the powers of judges.
In the corruption case, Sarkozy faces up to 10 years in prison and a millionth fine. The process should be completed by mid-December.