Soon drunk drivers may be caught before they even get home and before they even realise. A new roadside laser may be able to detect alcohol vapour in moving cars, working like an automated speed camera, but for boozers.

While the study that uses this laser found it was accurate to alcohol concentrations above 0.1 per cent, real-world use may have issues. If a passenger was drunk, or alcohol was spilled in the car, for example, that would fool the machine.

So in its infancy this device could be used by police to narrow down the number of cars it stops on suspicion of drunken driving.

The detector works using a laser and a mirror. The laser passes through the car and is bounced back by a mirror on the other side of the road. This allows it to detect even small concentrations of alcohol. But not small enough as 0.1 per cent is still above the legal limit of 0.05 per cent (in the US). Although scientists say this was done with a source less warm than a human lung so real world examples may be even more accurate.

We don't expect to see these on the roads anytime soon but it's probably best to avoid all drinks before getting behind the wheel, just in case.

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