South Australia Introduces Random Drug Testing On July 1st

Here's the TV ad the gov runs;

www.rta.nsw.gov.au...

Here's a few highlights from here; (about 10 pages)
www.findarticles.com...

Motorists passing a checkpoint who are pulled over for preliminary roadside breath tests are selected in haphazard fashion, and in most jurisdictions, all drivers who are pulled over are asked to take a breath test, regardless of the type of vehicle they are driving or their manner of driving; refusal to submit to a breath test is considered tantamount to failure of the test.
No attempt is made to detect symptoms of alcohol use through observation of behavior, as is the practice after a driver is pulled over at sobriety checkpoints in the United States.
Drivers returning a negative breath test result are not detained and usually drive away after a delay of less than 1 minute.
Drivers who test positive during a preliminary screening are detained for a more detailed breath analysis that provides a reading that can be tendered as evidence in court. A reading of 50 mg percent is the "prescribed concentration of alcohol," in most parts of Australia--that is, the level prescribed in the legislation beyond which it is illegal to drive.
Under mobile RBT legislation operating in New South Wales and Victoria, police are authorized to pull over any motorist at any time, regardless of the motorist's manner of driving and regardless of whether an offense or a crash has occurred. Once a motorist is pulled over, mobile RBT operates in the same way as stationary RBT. The major differences between the two forms of RBT are that mobile RBT is much less visible to other motorists and results in many more positive tests than stationary RBT.

I belive the US is considering a similar program

FATMAN