I lifted the following from the AA Website:
For some years now it is has been strictly forbidden under
article R413-15 of the French 'Code de la Route' (highway code) to have a speed camera detector in a vehicle in France, regardless of whether or not it is being used.
Penalties can include fines of up to €1,500, confiscation of the device and of the vehicle.
Until recently this legislation didn't apply to satellite navigation or other GPS-based systems capable of displaying fixed speed camera locations as points of interest (PoI).
New law in France Effective from 3 January 2012
French laws prohibiting drivers from carrying devices capable of detecting speed cameras have been extended to include devices able to warn or inform of the location of speed cameras e.g. satnav or gps systems capable of showing speed camera sites as PoI.
As well as now banning all devices capable of warning drivers of speed camera locations, the French government is installing around 400 new fixed speed cameras and is taking down road signs indicating the location of existing fixed speed camera sites. What should you do If you have a satnav capable of displaying French camera locations in France then you must at least disable camera alerts before driving in France. We recommend that you contact the manufacturer of the satnav for advice as it is likely that a software or database update is available that will actually remove camera data for France from the device.
If you have a satnav system built into your car then we recommend contacting the vehicle manufacturer in the first instance. Further advice Driving regulations and customs in France are different to the UK. There are severe and rigidly enforced penalties for all road traffic infringements. These include imprisonment and a heavy fine for causing death whilst driving over the alcohol limit or under the influence of drugs.
There are also similar penalties for causing death by dangerous or negligent driving.
The French police apply speeding restrictions strictly and if you exceed speed limits you will face heavy on-the-spot fines.
If you break French driving laws you can also have your UK driving licence confiscated by French Police. This could lead to your vehicle being temporarily impounded if no alternative driver with a valid licence is available.