Fred, in Australia they have a road side test that the police do on your saliva.
If that shows up any drug in your system, you then have a blood test to determine the level in your body.
Here, drug driving is treated the same as drink driving.
This was introduced following research showing drugs played a large part in the road toll.
It takes about three days for pot to fall below detectable levels.
Your friend needs to come up with a pot plan.
