Perhaps I’m a bit late, but thought I’d explain the notion of a “suspension” of a driving licence in France.
There are two types of suspensions : administrative (done by the préfecture) and judiciaire (done by a court or in this case "tribunal de police).
If you commit a serious speeding violation, which was Derek’s case, the police confiscate the licence at the roadside. They then give it to the Préfecture who have 72 hours to decide on the length of the administrative suspension. Any suspension over 2 months carries a mandatory medical.
After the administrative suspension, you get your licence back and can continue driving.
Later on (sometimes up to a year later if they are busy), the case is heard before the court (normally in your absence), and they decide on a fine and suspension to impose.
This is normally done through a procedure called an “Ordonnance Pénale”, which is essentially a fine issued by the court, which you receive by registered letter.
The administrative ban already imposed is deducted from the final “judicial” suspension.
In Derek’s case, if the court decides on a 3 month ban, he will be able to continue driving as he has already “served” three months.
However, if they were to impose 4 months, he would have to hand in his licence to a police station for an additional month to make up the full time of the ban.