The idea behind France’s in-car breathalyzer
The device was meant to turn an abstract rule into a decision a driver could make before setting off. A disposable breathalyzer typically uses a tube and a chemical indicator: the driver blows into it, and a color change gives a rough indication of whether alcohol may be above the legal limit. Keeping an unused one in the car meant it would be ready for that check—not something a driver had already used and could no longer rely on.
That distinction mattered. The kit was a prompt to pause and check, not a guarantee that someone was safe to drive. A result can be affected by the device and how it is used, and a borderline reading is no reason to treat driving as safe.
What changed when the penalty went away
The rule became less consequential in practice once failing to carry a kit no longer brought a penalty. That is different from a roadside breath test: police testing and the legal limits on driving after drinking are separate from whether a driver has a personal tester in the vehicle.
For visitors, the episode is a reminder that a country’s road rules can include both enforceable requirements and measures whose practical force changes over time. A breathalyzer may still be useful as a cautionary tool, but the reliable choice after drinking is not to drive.
