Starting July 1, if you want to drive a car in France you'll have to have not just one, but two breathalyzers in the car to test the level of alcohol in the blood. If you rent the car in France the rental company will provide the necessary devices, but if you rent in another country you're on your own.

The idea is that drivers should be able to self-test to determine if they are fit to drive. Two breathalyzers are needed because if the first is used the driver still must have an unused one in the car when stopped by the cops.

The legal limit in France is 50 mg per 100 ml of blood, lower than most places in U.S. (80 mg). It has been reported that the devices will be available for sale at entry points into France. If caught without a breathalyzer the fine is about $17. The penalty for driving with a blood-alcohol level exceeding 80 mg is about $5,000 plus possible imprisonment.

We will say more about this when we know more.

Read more about blood alcohol limits in the U.S., France and other countries.