What if you drink one beer and get into the car? The thing won't let you drive? Too much danger in having to pee fifteen minutes down the road?

These devices cost in the neighborhood of $1,500 each. That's a pretty steep price for a piece of mandatory equipment, especially for those of us who are basically non-drinkers (I average less than 1 alcoholic beverage per month) and own multiple vehicles. And besides, as you mentioned, it wouldn't be too hard to circumvent the device. So why punish all drivers by adding a costly device to their vehicles when we already know the device will not have its desired result?

I think they have actually implemented this in some countrys and only people who have been convicted of 'driving under the influence' have to install them in their cars. They got around the problem of the drunk driver using air in a balloon to sucker the device by programming it so that he had to blow a specific sequence of breath pulses into it which was individual to him and which would be difficult to teach someone else after he has rolled out of the pub. Would also be very difficult to replicate this using a ballon when you were drunk.

Volvo are developing just such a device that does not allow the engine to be started if a positive reading is taken from the driver.