From July 1st 2012 it is compulsory to carry a breathalyser kit in the car. Two kits per car are advised as the kits can only be used once, so if you use one you will need a back-up. 11 euro fines for non-compliance will be levied from November 1st 2012.
When driving in France, drivers are required to carry :-
Spare Bulbs Country of registration sticker High Visibility Jacket (must be kept in the car, not in the boot) Headlamp Converters Warning Triangle