"It's not illegal when the President does it" is a famous quote by Kissinger about Nixon during the Frost/Nixon debate, but, unlike how its generally used (ironically), it does have some merit. A president is not just the person - its the office. You can hate the person, but you should not disrespect or shame the office.
Jacques Chirac was appropriately granted immunity from criminal prosecution while president of France, although the judicial decision was controversial, it was decided that he would not have to answer questions that would be incompatible to his presidential functions while he served as president. Once he left office he was charged and convicted on charges of corruption and embezzlement.
Yes, Jacques Chirac was appropriately granted immunity from criminal prosecution while president of France, because it is necessary to make sure that he is not harassed while trying to do his job. If he were able to be prosecuted, he would constantly have people attack him. He needs to be able to focus for the good of the country.
Even presidents shouldn't be above the law, even the president of France. Jacques Chirac was granted immunity and that may be legally correct, however that doesn't mean he wasn't guilty of embezzlement while in office. Chirac was found guilty after the fact of abusing his office while mayor of Paris. Although he escaped punishment while president, Chirac faces jail time if he misbehaves during his suspended sentence.
No, he was not appropriately granted immunity from prosecution, and if he had been simply a citizen he would have been prosecuted. Since he was the president though, and has a lot of power, he can get away with a lot of things that most people could not, since he leads the country.