Starting 01 July 2012, every driver in France needs to carry an alcohol testing device (breathalyzer) in the car. This applies not only to local residents, but to tourists and business travelers as well.
You can buy this one-way gadget for about € 1,50 at most pharmacies, discos, and gas stations.
Not carrying one in the car will get you a fine of € 11,–
More about this on Focus.de/auto/news in German.