[BigJono]

> though I suppose if the car is driving itself perfectly fine police would have no reasonable grounds to pull anyone over and discover they're drunk in the first place.

I can't speak for America, but here (Australia) I'd guess the vast majority of drunk driving tickets are from booze busses. I can't even remember the last time I saw somebody pulled over and breathalysed.

[harpastum]

Could you elaborate? What's a booze bus? In the US, It's a pretty common occurrence to see someone pulled over and breathalyzed if they're driving erratically.

[mctx]

A booze bus is a random breath test - the police have labelled busses that they park on the road. I believe if you blow over the limit then you get on the bus and are tested again in 30 minutes.

They look like this: http://www.ranted.com.au/wp-content/uploads/2012/09/109890-b...

[eon1]

This may be the case in Melbourne - in Sydney cops aggressively breath test anyone who looks "suspect" (eg. P plates, any visible modifications, male w/ long hair, athletic wear) or who is "the right person at the right time" (say, if you're driving a utility around 4-5pm - many tradeworkers have a beer or two after work before going home).