Do not forget this new law for France! With effect from lst July 2012 it will be a legal requirement for all vehicles driven in France to carry a breathalyser kit. Note, this applies to everyone driving on French roads, whether you are resident in France, on holiday or just passing through.
One good note, anyone caught without a kit will not immediately face a fine. Police will start issuing the fines from November 2012. This is to give everyone enough notice of this new law and to kit out their cars.
It may be adviseable to carry two kits, just incase one has to be used, you will still have a spare.
The kits are for drivers to check themselves if they have enjoyed a business or holiday drink! If you fail do not drive! Police will still use their own breathalysers when carrying out roadside tests.